Spy Disguise Exploit

A new spy exploit has been found in Team Fortress 2. A spy can attack with his butterfly knife or revolver and maintain his disguise if he changes his disguise and then makes his attack before the change completes. The spy can only maintain disguise if he waits at until about 1 second before the disguise change finishes.

The easiest way is to wait until the sound finishes playing before you attack. This exploit is all about perfect timing and is very hard to pull off.