Let's be honest here, some football fans haven't the intelligence of a chimpanzee. Think of other sports such as Cricket, Rugby, Motor Racing, etc and you will find a more civilised intellectual audience.
You don't see any trouble at these sports either, i have yet to see A worcester fan trying to bounce a brick off a warwickshire fans head.
Footballers were the thicko kids at school with dandruff, snotty noses and shirt tails hanging out, and some of the fans are the same.
I have been to Albion games when fans having been slagging off one of our players for twenty minutes until someone has pointed out he wasn't playing.
Put it this way, football fans would never have put a man on the Moon, then again, i'm not sure Americans have.