Sounds like that could have been me XD though it probably wasn't
Playing spy now is even more rewarding. A good spy will strike a level of paranoia that might just win Your team the game all by itself ( snipers checking their back constantly, people spychecking others instead of shooting the enemy, being caught unloaded after a spycheck as demo/soldier/engie...etc etc. ). And when everyone does that, he'll just switch classes to sniper and headshot the people who move predictably due to spychecking XD
Also, it's kinda cheap, but... a global macro that turns Your "choose weapon X" to "choose weapon X + press >last disguise<" works wonders. Won't do anything for non-spies and needs only a minor gamepülay adjustment for spies... but allows for weaponswitch-spam. ANd it will take a loooong time until people finally realize that rapid weaponswitch =|= "I'm not a spy" anymore. Convincing a soldier that just fired a rocket in Your face that You are no spy, then turning around and stabbing him as he runs past makes me all warm and fuzzy inside
Big LOL @ facestabs still being an issue, though not so much now.