I thought about this and realized that with only one exception, this has been true with the men I've had relationships with. The ones that smoked would (back when they were single) sleep with anyone they wanted to just because they were attracted to them or wanted sex. The ones that did not smoke would save sex for meaningful relationships and/or some one they really cared about or had feelings for.
My friend said that the reason for this is that people who smoke don't care about their bodies or themselves. And people who don't care about themselves, don't care who they sleep with. I'm inclined to agree with this since looking at the sexual history of the boyfriends I've had over the course of my life seems to prove this. HOWEVER, I can't make that conclusion until I know it's true for women. MEN: THIS QUESTION IS FOR YOU. Have you noticed that the women smokers you dated were more likely to have a past (or present) that included casual sex and the non-smoking women were only intimate with partners they were emotionally involved with and/or in a long term relationship with?