Unbrained new players
That's not new, every time a game turn free the community get a lot worse. But frankly, when you are being kicked because you leveled a charger, you bashed a hunter or you cut a tongue, that's really REALLY annoying. 20- Hours players tell me what to do and cry every time I'm a cheater. Can you just shut up 100 hours more and learn gameplay mechanics before shout every time "CHEAT !" ?
Yes, you can cut Smoker's tongue, yes, you can bash Hunter and Jockey while they are jumping, yes you can one shot a charger with a melee (level), yes you can kill a witch in one shoot.
For god's sake please Valve make tutorials for L4D2, I laugh no more when I see a player as a hunter who run to me for a hug. How many time did I see a jockey crouching like a hunter before jump ? How many time did I trolled a Tank just by running in circles around him ? ....