We've all had those days. You connect to a server, pick a team and class, and soon you realize that the enemy team has at least 4 Spies.

Sure, most of them suck. They're the guys who played the tutorial and became convinced that they are James Bond. They only manage to get a single backstab on someone who wasn't contributing a whole lot anyway, like that F2P bow sniper who was dancing around the front lines instead of, uh, sniping. But they're annoying. They make things much more difficult than they need to be by managing to sap all the buildings in a nest and, after they're dead, the Engie can't get the sapper off the last building in time. They occasionally get lucky and backstab your Medic just as he's about to make an Uber push. You really want to tell these guys to get off Spy and do some actual work helping their team, except these minor successes have reaffirmed to them that they are indeed James Bond.

Have no fear; this guide contains comprehensive strategy for spychecking, regardless of class. Learn these tips and you will be able to weed out all but the most skilled and lucky spies. Who knows, maybe you can get one or two to realize that they suck.

Here are a couple general tips on spychecking, regardless of what class you're playing. The average Spy makes a number of mistakes in his game that indicate he's a Spy to the experienced eye.

1). In most circumstances, your team will usually be holding a position in close proximity to the Engineer nest, with few people willing to venture out too far lest they encounter the other team in its entirety. Most maps have a general geographic feature that defines this territory; in Upward, it's the exit to the underground area where the cart has to pass through. In Mountain Lab, it's the giant archway.

If you see ANY friendly player come towards your side from that geographic feature while facing your side, they're worth a spycheck. The average Spy doesn't bother trying to be extremely convincing. This applies especially if it's a friendly player that should be on the offensive, like a Scout, Demo, or Soldier, and would logically then be facing the enemy side, waiting for somebody to pop their head out. This especially applies if they're coming directly for you or the Engineer nest.

Fire a shot at that friendly player if they're coming toward you or your general direction. It doesn't even need to hit them; if they moved out of the way, they're probably a Spy, since a real friendly player wouldn't bother. If it's a projectile, like a rocket or grenade, it'll blow up as soon as it hits them and you've definitely got a Spy on your hands. If it's a hitscan weapon, you've got no obvious indication, so proceed with the class-specific tips listed below.

2). During the setup phase, take a look at the other team's composition. You'll see average Spies standing there, in disguise or just knifing the gates. Count how many there are and note their loadouts. Note if any are carrying the Eternal Reward or Wanga Prick, as these will be slightly more annoying than the rest. Keep general track of these guys, when they die, and whatnot. If there are only a few, then once you've gotten rid of all of them in quick succession, you will have a brief period where you don't have to worry about spychecking.

Note that you won't see outstanding or competent Spies; these ones will make sure to conceal their presence on the team with a friendly disguise or not going to the gates at all, and they're not worth your excess trouble to locate until they start to cause problems.

3). If you see any friendly player with no cosmetics and the default loadout, you should probably Spycheck them. If a Spy disguises as a class that your team has nobody playing, they will appear as such, so there's a good chance that a generic friendly is actually a Spy.

Similarly, keep track of your team members and what classes they're playing. If you see the name of a friendly player over a class that they're not playing, they might be a Spy.

On top of that, some Spies won't bother changing disguises, even if they've been caught in the same disguise several times. If you make a successful Spycheck on a particular friendly, keep an eye out for that same friendly and Spycheck him again next time he shows up.

4). Most Spies stick to a few key disguises:

The Pyro ("Who would suspect that the spychecker is the Spy?")
The Engineer ("Nobody would think the Engineer being around the Engineer nest is suspicious!")
The Medic ("People will be coming to me for healing but I'll backstab 'em instead!")
The Sniper ("I'm supposed to be in the back, so they'll never see me coming!")
The Spy ("I'm so clever!")

All these classes as disguises have VERY obvious tells. A Spy disguised as a Pyro won't actually be spychecking anyone, and a Spy disguised as a Medic won't actualy be healing anyone. A real Engineer shouldn't be that far away from his base anyway; in fact, the real one probably is still there, which is going to be real awkward when the Spy gets there. Real Snipers don't run out of the enemy side when they should be by the base anyway. Conversely, real Spies should be all the way behind enemy lines, doing real work, not hanging by friendlies and giving away their identities. Keep these tells in mind, and keep an eye on these classes.

From Golden Lightbulb Pyroshark:
"in my opinion, i feel like i always go scout. is it because of that tiny speed boost or somethin'?"
I left this out of the initial guide because I thought it was obvious. Any Scout that is running abnormally slow is a Spy, no doubts about it. A Spy disguised as a Scout STILL RUNS AT THE SPY'S RUNNING SPEED. Even with no boost on the Baby Face Blaster, a Scout still moves at like 120% speed. Sorry bro, there is no "tiny speed boost" to speak of.

5). Occasionally, you will see a friendly running toward you being followed by an enemy player. That friendly is almost always a Spy. Firstly, the enemy is not firing at him at all. Secondly, the friendly is not running backward and firing at the enemy. A friendly and an enemy coming out of the enemy area together is a dead giveaway that the friendly is a Spy.

The average Spy - any Spy, in fact - shouldn't be bothering you at all, since you're too fast for them. Their attention will be on other, less agile classes, meaning you have a good opportunity to take out Spies before they get the chance to do anything.

The Scout can overtake anyone in the game, besides maybe another Scout with full Baby Face Blaster boost. To this end, if a friendly player is moving in your general direction and you suspect that they're a Spy, change course and run into them. If you bump into them, shoot immediately, since you've just discovered a Spy!

A potential Spy moving the other way may be a little more difficult. If you're confident in your aim, you can try hitting them with the Sandman's or Wrap Assassin's ball, or the Mad Milk. However, the quickest and easiest way to spycheck a fleeing friendly is to take two potshots at them with your primary weapon while moving toward them. You'll close on them quick enough to get within the highest damage range for the Scout's primary weapons, and two shots (or three if you're a little further away) is enough to quickly dispatch a Spy.

Additionally, you don't even have to hit with both shots. The average Spy will assume his cover has been blown, even if he's not quite dead yet, and will immediately react to being shot, thus confirming his identity as a Spy. You should notify your team accordingly.

You are a bigger target for Spies, given your destructive potential and generally slow movement. Watch your back. In fact, that's a really good policy for other reasons. If you turn around and see a friendly headed right for you, facing your way, blast 'em with that rocket launcher of yours, and they'll probably blow up, because a real friendly won't follow you that closely (in fact, you block a real friendly's view of what's up ahead).

Other than this, the easiest way to spycheck is still with your primary weapon. If you encounter a potential Spy that doesn't see you, you could try hitting them with the Disciplinary Action (a Spy won't grant you a speed boost), or shooting them with your secondary and get them to think their cover's been blown. However, the rocket launcher is still your best bet, as it accomplishes the same thing as a shotgun shot and does more damage besides. If you're lucky, you might be able to gib that Spy in a single shot.

In addition, make sure to fire into corners and cubbyholes where a Cloak And Dagger Spy might hide out and wait for people to pass by. Your splash is big enough to cover the entirety of most of these spaces, and if you don't land a one shot kill you'll still see the silhouette of the Spy as he takes damage.

If you're using a banner in a big group of your buddies, keep an eye on your teammates. Unlike friendly Medics and dispensers, Spies can't leech off your banner, so any friendlies who don't have the banner's glowey-glowey visual effects when it's active are Spies. Kill him quickly, and if you can't then tell your teammates quickly, because if a Spy's already in the banner radius he's dangerously close and needs to be dealt with immediately

You're the go-to guy for a spycheck. I'm assuming that you know to give everyone you encounter a puff of that flamethrower, since Spies will catch on fire and friendlies won't.

Spies know how dangerous you are, and will generally avoid you. If you see a friendly turn a corner, see you, and then run away, give chase to the Spy, or at least alert your team. You're also likely to run into yourself, as the Pyro is one of the average Spy's frequented disguises. Spycheck other friendly Pyros you happen upon.

Like the Soldier, it's a good idea to sweep the flamethrower across little corners and hidey-holes to check for cloaked Spies. Additionally, Engineers will appreciate it if you swing by the nest now and then to give it a thorough spraying-down. Be liberal with your ammo, don't worry about running out, since this game has plenty to go around.

Be careful of Spy-Cicle Spies, as they are initially immune to your fire. The easiest way to identify a Spy-Cicle Spy is to keep blasting away. The average Spy will flee the spycheck, like if he got shot, despite his temporary fire immunity, so if he runs away he's probably a Spy and you should act accordingly.

From LAZER PENGUIN:
"In the pyro spychecking section, it may be worth noting that the spycicle makes a decently loud noise when they're sprayed"
This is totally true, and also sometimes the Spy will automatically scream that he's on fire. Follow up on this sound if you hear it. On that same note however, the fire immunity lasts a semi-decently long time, so you might want to not bother chasing him, since the Spy-Cicle needs to cool down (so to speak) and in the recharge interval, the Spy is robbed of effectively half of his most important function tools, and if he comes back to sap buildings without a way to quickly dispose of the Engineer then he's just asking for trouble.

Demo spychecks are similar to Soldier spychecks, since they're generally similar classes. Remember to watch your back and shoot at anyone running straight toward you, and if you want to be extra useful, lob a grenade into the odd crevice here and there.

Spies are a good way to rack up heads if you're using the Eyelander or one of its reskins, but unless you're certain you can kill the Spy, you should rely on the high blast damage of your primary weapon.

If you're playing as a defensive Demo and you don't have a better place, you can place some stickybombs around the Engineer base and listen for "Spy sappin' my sentry" before triggering a detonation. If you placed them right, it should be literally impossible for a Spy to escape the blast radius, thus saving the Engineer the trouble of hunting that guy down before desapping and repairing his buildings.

Your melee weapon isn't any better for spychecking than anyone else's, so don't bother. You also shouldn't bother trying to spin up your minigun just for a spycheck, so if you're revved down you might want to consider switching to your shotgun (if you're not using a lunchbox) and give the suspected Spy a couple shots of that.

However, if you're in the heat of battle (like you should be) the easiest way to spycheck is to turn the minigun toward the suspected Spy for a little bit. Treat friendlies that you are spychecking the same way that you would treat the Spy if he was undisguised; a second or two of minigun fire should take down almost any Spy, and those that survive will be scrambling for health, as opposed to a real friendly who wouldn't even notice and would continue doing whatever it was they were doing.

Watch your back, even more than the Soldier or Demo, since you move slower than either of them. Remember not to let your guard down, even if you're focusing on doing something else, since even the worst Spy can get you if you're distracted. Remember that the Huo-Long Heater WILL NOT SAVE YOU, it will only ignite Spies that approach you (although having it up and firing may occasionally deter the less bold Spy here and there).

Sometimes, you'll be in the heat of battle and slowly strafing back behind cover when you'll all of a sudden get stuck where there should be an open passage. In all likelyhood, you've bumped into a Spy. You should immediately turn around and take him out, as the fact that you have yet to be backstabbed indicates that he was probably cloaked and will take a bit to get uncloaked. In that brief interval, the minigun should be able to kill him in such close range.

You are one of the Spy's most frequented disguises, so look out for clones of yourself. If you're on a defensive team with multiple Engineers, be wary of building your base right next to others', as this will increase the number of Engineers running around in the same area and thus lower your guard to them.

Pay extra attention to who approaches the base, and how they do it.
-Friendlies with full health
-Other Engies, coming from the front lines, as opposed to spawn or a source of metal
-Friendlies with absurdly low health

While Spies don't control any of those things, they are all a tell for one reason or another. A friendly with full health has likely full ammo as well, so why would he need the dispenser? Conversely, a friendly with absurdly low health probably won't wait for the dispenser to heal him all the way, so he'd seek out a health pack first to give him a boost. Engineers really have no business being on the front lines.

Friendlies who approach while looking right at you or the sentry should be spychecked as well, as a real friendly has no business staring at your sentry gun like that. The average Spy will sap everything in sight, so it may be worthwhile to, if you have no use for a teleporter, to create an entrance or exit somewhere where potential Spies would see it and sap it, as an early warning system.

An Engineer lacks a really quick and easy way to actually spycheck and subsequently kill the Spies he discovers. If you have the Widowmaker, the metal-refill function may serve as a tell, or the Southern Hospitality's bleed effect. However, if you're camped close to your own spawn, consider letting the Spy kill you within your sentry's line of sight but out of sap range, and then just respawning, as the Spy will drop his disguise on attacking and your sentry will take him out swiftly and efficiently.

From Mr_Welldone:
"I would like to add some information. If you see an Engineer watching his own buildings get sapped, it's very likely they're a Spy."
You're wrong. If you see an Engineer watching his own buildings get sapped, he's definitely a Spy. Shoot him dead now. Additionally, if there's a lot of chaos going around a nest and all of a sudden buildings start getting sapped, step back and take a good look at all the people milling around the nest. The character model for the disguised Spy does a little "placing" animation when he puts the sapper on the building.

You're a huge Spy target, if only because the average Spy is convinced you are the most important target. You're also usually at the back of the attacking formation, staying behind cover so you don't get shot, so your teammates won't notice you've been stabbed until it's too late. Watching your back becomes even more important here. Note that your medigun will stay locked on target even if you turn around, so it's not a big deal to look behind you a lot.

An easy way to determine a Spy as Medic is simply to move out of their way, and if they turn to keep facing you, they're worth spychecking. Unlike other classes, the Medic should rely on his melee weapon, as opposed to his primary, to spycheck, since the Syringe Gun projectiles travel rather slowly and deal piddley damage, too little to quickly and efficiently dispose of Spies. However, the Medic does move slightly faster than the standard running speed, so you can probably catch up to the Spy. A Medic chasing a friendly around with a melee weapon out may also alert your teammates that there is a Spy in the vicinity.

Note that the on-hit effects of the Blutsauger and Ubersaw don't work on disguised Spies, so stay vigilant.

Additionally, the average Spy will flee if he sees you point something that's not a medigun at him anyway, so facing them and pulling out your primary weapon can work too, although you're not actually doing any damage in this scenario.

The health display for Spies is matched to their "disguise health," which doesn't necessarily reflect the Spy's own health. However, when a Spy calls for a Medic, the alert icon is colored to match the Spy's own health. Make note of this, and check to see if the ally's Medic bubble corresponds to their health display. On top of this, many Spies calling for Medic will watch you rather than keep fighting the enemy, waiting for you to turn around so they can kill you, so be wary.

You're very combat-weak, enough so that bad luck and bad reflexes could lead to even the worst Spy dispatching you in a one-on-one. Notify your teammates of the Spy's presence, and take a brief detour if you have to to eliminate him before continuing with whatever you were doing.

Spies are one of the Sniper's biggest annoyances, as it's hard to remember to spycheck frequently when you're so intent on plugging some heads. It's also hard to spycheck as a Sniper, as his primary weapons are no good for quick Spy elimination. Just remember to unscope occasionally and take a look around you.

It's good to stay far, far back from where everyone is, because then anyone who comes up to you at all has a decent chance of being a Spy. Most friendlies have no reason to look at you, so anyone who does is worth spychecking as well. The SMG and Cleaner's Carbine are good as spychecking weapons, as the average Spy will immediately flee when you turn toward him and switch weapons. Jarate is good for getting the cloaked ones if you have an area you want to clear out, but then you have to rely on your melee weapon and unscoped sniper rifle shots to finish the Spy off.

Overall, unless the rest of your team is absolutely awful and you're just scoring headshots left and right, you getting backstabbed is not as big of a deal as someone like the Medic or Engineer. Consider standing within the sentry's range (but not in the nest), so a Spy who decides you're a bigger target will get shot down by the sentry.

When you are scoped in on your allies' general position, keep an eye on their behaviour. If a particular friendly is running straight toward the backs of the Medic/Heavy pair, or even dancing around behind the very front lines and not firing, it's not a bad idea to try shooting him, since it's possible he's a Spy. I can guarantee he didn't know you were there if he was undercover among your frontline allies. Note that the hitbox of a disguised Spy doesn't line up with the hitbox of the disguise class. To that end, you should make sure to charge your shot fully and aim for the body when spychecking from a distance.

Additionally, you may notice undisguised Spies in places that your allies do not. These are to be taken care of immediately.

You have really no business spychecking. Your job is on the other side of the battlefield, so you shouldn't be encountering enemy Spies at all. On the other hand, the average Spy doesn't really think about the fact that anyone else might be playing Spy, so unless you make your presence extremely obvious, they won't be looking for you. If you're on the defending team and the enemy doesn't have a nest, consider hanging out around your side and doing some counter-espionage.

Since enemy Spies aren't considering your existence, you can walk up behind everyone who looks like a friendly with the knife equipped, and if they become a valid backstab target, they're a Spy (who you should dispatch accordingly). The L'Etranger has the cloaking bonus on-hit effect, and the Ambassador can be used to spycheck in the same way that a Sniper uses headshots. Running into people is also a viable tactic, as the average Spy doesn't wonder what a member of his own team is doing fraternizing with and passing through the enemy. However, be sure to change your disguise when you decide to go backstab some enemies on the other side of the battlefield, because above-average Spies will know who you were disguised as among your own team and may have communicated the information to their friends.

You should make every attempt to eliminate Spies you find. However, don't be obsessed with it. Many a game has been lost by four or five teammates getting completely distracted by a Spy that got away and wasting valuable time trying to find him. If you uncover a Spy and he gets away, simply notify your team and be a bit more careful. The average Spy will attempt the same tactic he tried last time (possibly even with the same disguise), so you can get him then.

Be aware of Dead Ringer Spies. Go into advanced options and turn on damage numbers, and take note of the amount of damage you do to Spies. If a Spy dies of something that seems inappropriately measley damage, assume he is using a Dead Ringer and stay alert. Examples of inappropriately measley damage:
-Scout - A single scattergun shot
-Soldier - Splash damage from a rocket (as opposed to a direct hit)
-Pyro - Less than a second of flamethrower
-Demoman - Splash damage, or fall damage after he gets blasted into the air
-Heavy - Less than a second of minigun fire
-Engineer - If he dies the second he enters sentry range
-Medic - Less than one full clip worth of syringes
-Sniper - A single kukri hit, or less than a full clip of the SMG
-Spy - A single revolver shot or knife stab (butterknifing)
Note that these are mostly safety estimates. It's entirely possible that the Spy is dead after these, but you should be on your guard just in case.

Additionally, if you have the hit noise on, no sound will be made when a Dead Ringer goes off. If you see a kill attributed to you in the killfeed that didn't have a "ding" to go with it, or you see a Spy ragdoll go flying without accompanying "ding," that's a Dead Ringer. Notify your team accordingly.

Some people script their games to automatically disguise when the Dead Ringer goes off. While it does save valuable time, it creates one of the most obvious tells you've ever seen in your life, as the disguise smoke will appear and continue walking wherever the Spy went as he drops his fake corpse. Don't ignore this and go about your business; remember that the Dead Ringer boosts damage resistance, and if you keep letting that Spy go off and grab ammo and come back (likely with refilled health as well), you're never going to get rid of him.

If a Spy also seems stupidly reckless, such as just running out of spawn undisguised with the knife out, they're probably a Dead Ringer Spy as well.

Note that if you're a Pyro, you should keep your flamethrower firing for a second or two after seeing a Spy die, just as a precaution for Dead Ringers, as they will be lit on fire again.

NEVER assume that you're safe after a single successful spycheck. It's entirely possible that you're facing down a "Spypack" team with 3 or more Spies, so continue to be careful.

Beware of trickstab Spies. These Spies are a unique breed that seek to prove their l33t skills (to whom, I'm not entirely sure) and won't try to sap or backstab important targets. Rather, they will reveal themselves to you as a Spy, or camp at the peaks of staircases, and try to get you with a trickstab, which are backstabs made through clever manipulation of the backstab-registering mechanic in the engine. If you see a Spy who isn't attempting to be subtle, or are chasing a Spy headed toward a staircase, don't fall into his trap and chase him around or follow him up the stairs.

From: Heavyman25:
"multiple times he forgets to mention cloaked spies :P"
...The thing is, it's pretty much impossible to detect a cloaked Spy. Which isn't that big of a problem because a Spy can't actually do anything while they're cloaked. Thank God. Do keep an ear out for the sound of decloaking Spies. If you pay attention it's more obvious than you'd think, especially Dead Ringers, which are absurdly loud. If you hear a Spy uncloaking, get the heck out of there and tell your team there is a Spy lurking about.

Well, you've made it all the way through this guide! This is the first time I've ever written a guide. Hopefully the tips help. Leave your comments below please on how I can improve this, and any other anti-Spy strategies that you find work. I'll try them out, and if they work I'll add them to this guide!

EDIT: I saw this today and I figured I'll nip it in the bud. There have been a variety of comments, mostly positive but increasing in haterz as this guide gains viewership, but today I saw my first "text picture comment." Please note that I consider comments with the thumbs ups and doges and stick figures to be spam and they will promptly be deleted. As for you people who say "JuSt wM1 pYr00" or similar such things, think of this as refining your crude and uncivilized methods.