Every situation is different. I have met girls while I was on vacation. Shot the shit with them and exchanged info. Once home we would talk, IM, and email. When I would go see them it would technically be the first date. In reality though, the "courting" process has been going on for a long time. So I don't think less of them at all.
I have met strippers before who have gf's. Every once in a while they want the cock. They know exactly what they want and wait for it. When its you they tell you. You know going in it is one and done. You have to respect the girl that knows what she wants, how she wants it, and gets it!
I could go on and on. Every situation is different. The only girls I don't respect after are the girls I don't respect before!!!