Protoss players usually have any of the following qualities:
1) Balding or having a very short hairstyle.
2) May have a tattoo to show others he is a Protoss Player
3) Limits his playing style to Cannon Cheese or massed Void Rays
4) A n00b
5) Shirt is usually sleeveless
6) A dork
7) Breathes through the mouth exclusively
8) When he inevitably quits out will have thousands of unspent minerals and gas
If you spot a Protoss player in the wild call the nearest Terran player to beat him with massed marines.