I'm not taking up for it. I think there are limits that fans should respect, but I understand why so many do stuff like that. They think that since they gave their money to attend, they can do whatever they want in terms of chants, etc... Love it or hate it, to many it's just part of the fun of going to a show. Heck, check out some of those ROH crowds.
In the defense of "the fans", there are times when a show is so bad that the only entertainment comes from the fans.