I think that when it comes to chosing friends, people you learn from, people who you hang out with, people who you teach, hire, work for, whatever, you should always be open-minded. Don't go by stereotypes or even first impressions. Respect everyone and treat them like they've got the potential to really help you out, no matter where they're from.
Dating is a totally different matter. I've been accused of being "hung up on ages" and social classes and all that when it comes to dating... you know what? I think that's okay. There are billions of people in this world that I'd be totally happy working with or spending time with, but not dating. I think when it comes to relationships, we should allow ourselves whatever quirky random stupid judgements we want to cast on potentials. I was friends with a girl in college whose friend totally bitched her out because she refused to date a non-christian. Who cares? It's her deal, there are plenty of christians out there to date, it's not that she respects non-christians less, it's just a choice and it doesn't hurt anybody. Hell, 99% of the population automatically throws out an entire gender from their dating pool, and they're going to critique her for throwing out a religion (or lack thereof)?
When it comes to dating I honestly think you can't have too many hangups. Can't be too picky. Friendship is one thing. Dating is totally different. Not everyone deserves a chance to date me, and I don't have time for the whole world anyway. If I want to throw out the poor, the short, and the young, it's my own business. My own loss, if any of those groups were worth it. If you don't care and you'll go out with anybody than more power to you. But it's time for society to quit lamblasting people for being "too picky"... I think we especially do this to women... "She'll never get married, she's too picky, she expects a guy to like, have a job and stuff. I mean how can she just demand that from everyone?" Please.