How do I know if a guy is actually a good guy?

Ok for as long as I've dated I've had really bad guys. They all seemed to use me in one way or another. I've found that now I'm paranoid that all the guys I talk to are gonna be like them. I need some help so I can actually tell when I start talking to a guy of it's for sex, to make someone jealous, or for rides. For example I'm talking to this guy now and he seems sweet, he was the one starting the conversations in the beginning. Then I got hocked and he never starts the convo anymore. I saw on his facebook that a girl wrote, 'we should hang out sometime ;)' he responded all happy and of course attitude. Hes been asking me to hang out all day and she wrote that the same day. Is this another guy using me?