Is it really as terrible to think you don't necessarily want to talk to someone because they're unattractive?

I don't think you're terrible..you can't help how you feel about a person, especially when it comes to like a social site or something. When you speak to the person, the first thing you see is their picture so there has to be something that intrigues you or something you like about them for you to be interested in them. Some may say it's shallow but I don't think so. I'm the same way. If I don't like a person, without knowing them, I can't force myself to want to talk to them either. It's different if it's someone you know and you get to know them and like them. So don't feel bad. Especially if you feel uncomfortable with how clingy he is. That's how you feel and no one can say you're right or wrong about that.