Spy-checking

From TF2 Wiki

Because of the Spy's ability to cloak or disguise as a character of the opposite team, it is useful to often check for the telltale signs of an enemy Spy in order to prevent them from backstabbing team-mates or sapping buildings.

Signs that indicate an enemy Spy

• A teammate stops when bumping into him (true teammates pass through you).
• A Medic without an ÜberCharge meter.
• A Scout moving at the Spy movement speed.
• Having your own name, or seeing your name yell a voice command that you didn't use.
• Having the name of somebody known to be elsewhere or dead.
• Having a name that does not correspond with the player's current class on the scoreboard. This happens when a Spy disguises himself as a class not currently on the team. It can also happen if the person has changed class while the Spy was disguised.
• Being surrounded by teleport particles of the enemy color. **REMOVED in 5/29/08 Patch - Teleporter effect no longer shows up on invisible or disguised Spies REMOVED**
• A non-Engineer standing on top of a friendly Sentry gun or Dispenser (team-mates cannot do this, Engineers can stand on their own buildings however).
• While cloaked, briefly glowing his team color when bumped or shot.
• Obstructing friendly contact projectiles such as Rockets and Pipe bombs. Such weapons will usually shoot straight through team-mates.
• Placing Sappers on friendly buildings.
• A friendly Pyro on fire (they are normally flame-resistant).
• Any player that is on fire will glow their true team colour.
• An enemy Spy will display a 75% health level when disguised as a member of the other team, regardless of his actual health. He can remove this clue by finding a medic of the other team, however, the Spy can never feign a health level less than 75%. Medkits and Dispensers can also be used although they only work if the Spy actually has less than 125 health.
• Being healed by an enemy dispenser while cloaked (healing "ribbons" are still visible).
• While uncloaking, the spy is briefly coloured in his own team colour until he's uncloaking is complete.

Signs that indicate that a teammate is not a Spy

• Able to be passed through, as opposed to stopped short.
• Shooting a weapon.
• Holding any tool/weapon other than the primary weapon (the disguised Spy can only display that class's primary weapon).
• A Scout moving at the normal Scout movement speed.
• A Scout double-jumping.
• A Medic with an Ubercharge meter.
• Being surrounded by teleport particles of your team's color.
• Entering the resupply area.
• Reloading.
• Taunting.
• Carrying the enemy Intelligence.
• A Spy indicated as wearing a disguise.
• A cloaked Spy that is visible to you.
• A Sniper with his Rifle to his eye (instead of holding it idly).
• A Heavy spinning his Minigun.
• A friendly player who is using their microphone (a symbol appears over the player's head).

Proving that you are not a Spy

This is short set of ways to stop your teammates from needlessly spy checking you.

• Switch to a different weapon (Spies in disguise only appear to be using the class's primary weapon).
• Shoot your weapon (a spy reveals himself by attacking).
• Agree to a sequence of moves in set up time (e.g. crouching twice).
• Taunt.
• Use your voice chat to say that you are not a Spy (e.g. "Just me").