People are not always what they seem. Don't let your first impressions cloud your judgement.
You shouldn't judge people before you get to know them. You should, I believe, judge someone after you've gotten to know them (Judge seems to have such a poor conotation, but I don't know what other word to use). No one says you have to be friends with everyone. Sometimes your beliefs are too much at odds, or you just don't like the way they treat you or your friends. The answer then is to not be their friend. HOWEVER. However, don't become enemies. There is no real reason you should have an enemy in life, the world hell even high school is a big enough place for the two of you to get by without much contact. Civility. Just remember that.