How do you determine if a girl is "girlfriend material" or just a FWB?

How do you determine the girls you would date & turn into a girlfriend/wife from the girls you just want to sleep with? It seems like every guy I meet just wants to sleep with me, and isn't interested in getting to know me. Is there something I could do differently to put myself into the girlfriend category instead of just being the girl they want to try to get lucky with? Is it that I'm meeting bad guys, and is all they are looking for at the moment, or am I portraying myself somehow in a way that makes all guys think I'm not girlfriend material?