The way I see it, the single defining characteristic of an elitist is the belief the refusal to be mediocre. This is no way mutually exclusive with being an asshole, idiot, retard, etc.
One interesting example brought up was WoW. Yes, there are a lot of asshole elitists that suck at the game. But if you look at any top level raiding guild, you see one unifying characteristic. They don't tolerate mistakes by anyone. If you don't pull your weight, you knew you were a liability. Nobody uses junk potions to save money, nobody raids in their sub-par grinding/pvp spec, everybody has the necessary professions to min/max everything (enchanting, leatherworking, etc.) The fact of the matter is, to really be a contender, you can not just say, "Everybody, you're all very good, do whatever you want" because the fact of the matter is, most people suck really bad. Especially in WoW...I never quite understand how people can be so bad at such an easy game.
It may be that I'm mixing up elitist and elite. But the way I see it, you don't have to be an elite to be an elitist, or vice versa. You just have to have the attitude that the way the majority of people do things is not the best way things should be done. I'm not arguing that everyone should be an elitist, I'm just arguing that elitists often times have something important to say that the majority of people don't want to say/hear.