Trash talking will be entertaining for all sorts of paying public in any sport as long they are confined to a certain limit. To ban racist and obscene actions and words, for example, will do only good to the sport and in the end I bet it will bring even more money.
The expression "real fight fan" is intriguing. I think this is a myth. UFC is interest in who pays, regardless of what makes you pay. So the "real fight fan" wouldn't stop whatching Diaz brothers fight if they were prevented from doing what they do, right? But I can see lots of potential paying public being lost by watching their deranged display.