I'm bad at dating. I fail horribly. It would be funny if my reputation/potential future with a member of the opposite gender wasn't in constant peril. I'm fairly open to who I want to date. I normally date people that I know and get along with pretty well. I try to avoid having crushes on people that I don't know, but attraction works in mysterious ways. It's hard to try to get to know people who you want to date (if you don't know them); going out with people you already know pretty well is the way to go. I've dated some really good looking girls and some just so-so looking girls. Like Claire said, if you like who they are, they become more attractive. My friend likes the quote, "You don't love a girl because she's beautiful, she's beautiful because you love her." And I agree. But I wouldn't date a girl that looked like a Koopa... I'm not that open...
In response to the question, I am a bit shallow. I do make observations of how good people look (in my mind, not outloud); I try not to let such observations rule my actions, but there are a few nice girls I know that I wouldn't want to date (for looks). Shoot me.