Constant harassment, insults, immature responses and language. Seriously I try trade to with someone and he says gtfo and learn how to play all because I didn't have any hats at the moment to trade. Some guy insults and calls me a (insert multiple swear words) noob and to go kill my self. Constant racism using the "n" word along with names with such words. And this is not just one or two times this happens ALL the time and It's not right that I can't even have a good game without being insulted.
You're just playing on a server that has awful players on it. It's not like that everywhere, trust me. A great many server even has pretty strictly enforced behavior rules too, if you're really that bothered by it.
Also, the TF2 community is one of the best and most generous communities out there, so get yer facts straight, sonny.