Those who hack and troll
Those who are 12 and pay money therefore taking it too seriously
Contrary to other descriptions, it is not ruined by the flood of hackers, but rather hacking makes the game. Hacks being free and widely accessible, yes, many people use them, but being a hacker is all that keeps the game interesting.
-Nah I'm playing Combat Arms cause using these new hacks and trolling 12 yr olds is really fun