Personality. It's really that age-long lesson we learn as kids: just because someone is ugly on the outside, doesn't mean their ugly on the inside. Appearance, especially in today's society, has taken over and people tend to label people by the way a person looks. "That guy's wearing dark clothing, so he's probably gothic, or emo, or just depressing." or "That girl is wearing a PINK shirt, so she must be a total preppy bitch." These are things I've heard all the time. It's sad, really.

Appearance is a major factor on how we judge a person, even before we know what sort of personality that person has. :/ Society has really made it this way; even though not everyone judges, you can't say it doesn't happen.