Why do I always get "those" guys?

I will never understand why when I meet guys or start to like them, they only want one one thing and one thing only. I am at that point where I want to find someone to have a serious relationship, I'm 30 and I've been single for a year now. It never fails though and whenever I think a guy is being genuine with his feelings, poof they either flake or they try and hook up with me and that's that. I am an attractive girl but I don't want my looks to steer guys in that one direction and it seems like that's what it does, I'm not sure, but that's my only guess. It gets old and I'm exhausted to the point of not trying anymore, but then again I don't want to be 35 with no one and no children. People tell me that they'd love to have all that attention from guys and that I always have someone if someone else doesn't work. Well that's great and all but nothing ever turns solid. When I think the guy is going that direction of just a hookup, I either don't hook up with them obivously or tell them my feelings, etc, especially if they tell me theirs, but I'm beginning to not trust guys because of that. So my question is, why does this always happen to me and what do I do?