This is always such a tough argument. I can't stand people who go to a game for the sole purpose of getting drunk and cursing and acting like morons. If you can't be a normal human being, stay home.... But on the other hand, the snobby, holier-than-thou attitude of the people on the other side of the argument is so over the top. It's one rung below "i'm a better person than you so I get to decide what's ok".
Devils Pride 26 has it right. You can't pretend you can stop all of the naughty words of 16000 other people. You need to understand that's part of a sporting event, however, people should also have the responsibility to know their surroundings, realize that they are in a public place, and try to act accordingly.
Having said that, I must add that heckling players, coaches, and the dirty evil cheating refs is every fan's god given right, and can be done quite creatively without having to drop f-bombs.