I've been TF2 on the PC a lot recently and I actually can't think of a single time where a person was excessively racist and/or homophobic through voice chat. It's pretty often that you'll get one who just talks constantly, sometimes people will start singing, and the new fad seems to be piping their mp3's through the microphone, all of which is extremely annoying, but not offensive. I have the incoming voice audio turned down 50% so that I can still hear it when everyone is being useful and working together as a team (which also happens often if you play on the right servers), but not loud enough to annoy me when someone immature gets on.