I absolutely do this and do this everywhere! I try to determine their personality from their faces. I rule out people (women) who look like they had their picture taken by "Glamour Shots" or spend way too much time (and money) on hair and make-up. I'm convinced that someone "like that" just won't "get" me. Or, at least that's what I've always told myself, so I believe it.
Stereotypes are wrong, but it's a hard habit to break.