I think I'm an intellectual elitist. I've never really had a problem with people who are a bit slow or who don't have the knowledge I take for granted as widely known, but I've noticed that I have an increasing tendency to think to myself (or, worse, say to someone else) that I don't think [person] is the sharpest knife in the drawer.
I'm not talking about people who intentionally limit themselves and are willfully ignorant, but the sort of person who just doesn't strike me as intelligent. For instance, one of the students has vowed to get me back for scaring her and her friends one night (ghost stories and an accomplice playing some tricks--good fun), and she said she had come up with a plan. She paused as though she had to think about it, then told me that she wasn't going to tell me what it was. I commented to a coworker that the girl didn't strike me as the brightest, and it hit me that I had no reason to believe that. After all, I don't know what was going through her head. It seems kind of silly to specify that she wasn't going to tell me her secret plan, but I say stupid things a lot. (Turns out, though, that she and her friends were watching one of those ridiculous MTV [or something like that...I don't know] dating shows tonight, which goes a long way to prove my hypothesis.)
I also realized that I don't know exactly what criteria I use to determine intelligence. It's just an instinct, as far as I can tell. While I'm generally correct (somehow) when I size someone up, I'm not 100% accurate, and it's not fair for me to figure someone's lacking without having some good proof.
I also really need to give myself some ground rules for determining common knowledge. If they don't know the relevance of the light slit experiment to quantum physics or the actual reasons for the Civil War, it's not because they aren't bright--those aren't the sorts of things everyone knows. Now, if a person can't do simple math or figure out the basics of sentence structure and punctuation, I have a basis for deciding they may not be bright.
I know that I probably won't stop sizing people up. I can at least try to stop myself from commenting on the intelligence of others based on very limited experiences. I make a fool of myself often enough to know that even an intelligent person can look pretty stupid.
Then again, if I hear them turn on some rap music, I feel I can adequately judge them to be lacking in the brains department.