I've had to change my gamertag because apparently it was inappropriate, but that's been it. What pissed me off is I had that gamertag for over two years and then a couple months after Halo 3 came out they all of sudden told me I had to change it. What, so it was appropriate the first 2+ years I had it? So for about the next five days after that, I had to change my gamertag every day until I found one they thought was suitable.
As far as suspending, I think it has to be for something they have concrete proof of, such as something you have written down either in a gamertag or profile. If people are complaining that you are trash-talking, they really can't prove you were because it could just be crybabies who are mad that you beat them and are trying to get back at you. Me personally, I only submit negative player reviews if someone quits out of the game and they are on my team or if they don't play the game the correct way. I just set them to an "Avoided Player" in hopes I don't get stuck with them again. I'll also be just as quick to leave a positive review if they play very well and have good sportsmanship. The only time I've filed a complaint is when someone uses racist language. There seems to be a lot of pussy closet K.K.K. members online who will quickly kiss a black person's ass in public but only have the balls to call someone a "nigger" when they are protected by being online. I'm white but those faggots will still call me that if I tell them to shut the fuck up. So then I just file a complaint. There's no need for that. You can talk all the shit you want, but don't bring it down to that level.