I disagree. Getting people pumped and selling tickets is no excuse.
As I've stated before, in something like WWF, I think its fine: most reasonable people realize it's all a show and the trash talk is part of that show.
In MMA events, everyone trains hard and risks serious injury and even crippling career-ending injuries, and on a given day ANYONE can make a mistake and end up eating a punch and ending up bleeding on the mat.
They all deserve respect from their opponents.
GSP entertains, he puts on a great fight, he sells tickets. I always go out to watch the events with GSP. And he has, as far as I've seen, always been a great sport, a class act.