Ooh, I've thought of something else to post here...
People who absolutely can't stand criticism of whatever it is they like. By this, I mean people who seem like normal fans and don't usually seem to think their fandom is "flawless", but if a few other fans start to say that they don't like something about it, this person can't resist bringing up the old standbys - they're "haters", they're jealous, they're going to break the fandom because the creators will be hurt and stop creating, they shouldn't criticize until they can personally do better, they should be glad that the fandom exists in the first place, they're going to drive others out of the fandom, and so on ad nauseum. I know that every fandom has people like this, but I'm still unable to understand the sense of it (well technically I suppose it basically has no sense at all) and it still grinds my gears. Everything in the world is imperfect, and no matter how much one likes something, there's always a chance that someone else might not like it. That doesn't automatically delete them from the fandom, it just means that they don't share the same opinion.