Spychecking refers to a number of methods to find enemy spies.
- Spies cannot clip through the enemy team. They will bump into them and around them.
- Spies don't move faster when disguised as a class like a scout, this causes their animation to look strange.
Class-specific spychecking methods
The Scout has decent innate spychecking ability. His speed allows him to catch up to his teammates quicker. The bump is a good indication if there is an enemy Spy, so try to run through as many of your teammates as possible. He can use his Mad Milk to highlight cloaked Spies. The Scout may decide to throw his Mad Milk when his team calls the position of the Spy, or when he bumps against the Spy to make him temporarily visible. The Mad Milk "dripping" effect will be visible to all teammates regardless of the Spy's cloak status, helping them to locate and kill the Spy. The Scout can also use the Boston Basher to hit suspected spies; if they bleed, they are a spy. The Scout can also utilize a form of tracking to detect a spy during its cloak.
The Soldier is generally not a selected target for Spies due to their uncanny nature. Soldier's can check corners and hiding spots utilizing the splash of their Rocket Launcher. The Disciplinary Action speed bonus will also not apply to enemy disguised Spies, use it to detect them. Rocket Jumping in itself is a great way to protect yourself from Spies nearby and even damage them by accident. Buff Banner effects will also not apply to enemy disguised Spies.
The Pyro is usually the single most powerful enemy a spy can face. A good Pyro will be capable of using his flames to consistently spycheck any suspicious target and therefore expose an enemy spy that may get too close. The fact that the Pyro's flames render a Spy's cloak useless and can quickly expose his position a good spy must stay away from a Pyro at all given times. In Highlander, the Spy's main targets are usually the Medic, Demoman, Heavy and Engineer given their strategic significance to the other team. Since a 9v9 Pyro usually sticks with either the combo (which often contains the three former targets) and helps protect the Engineer's Nest, this makes the Pyro a natural deterrent against a capable Pyro. Because of the Pyro's ease and effectiveness on spychecking duties he is often deemed responsible to protect his team from the enemy spy. However, with or without a Pyro, it is important to recognize that Spychecking is a team effort as a Pyro cannot be everywhere at once to handle the enemy Spy in all possible scenarios.
The Heavy can use his minigun's tracking ability to detect an enemy spy through his cloak. Natascha will slow down Spies trying to escape. The Huo Long Heater will set any Spy close to the Heavy on fire.
The Engineer can place buildings in doorways or other chokes that force spies to jump over and reveal that they cannot walk through the buildings. The Southern Hospitality causes bleed on spies and exposes them for a period of time long enough to kill them. The Pomson 6000 makes a drain sound when it hits a spy and drains his cloak.
The Crusaders Crossbow will not heal enemy disguised Spies, use it to detect them. Being in close proximity to them, a Medic should be able to determine an enemy Spy due to bumping into him. It should be common practice for a Medic to check anyone that comes within 5 feet of him for safety reasons, what with the Medic being a valuable target.
The Sniper can use his Jarate to cover enemy spies in dripping particles. The Spy will also turn a shade of yellow. The Sniper can also use the Tribalman's Shiv to make the enemy Spy bleed.
The Spy can use his knife to spycheck his teammates. If the knife raises in the position to do a backstab, than the "teammate" is an enemy Spy.