Hmm. I've had very few 'casual sex' experiences, and they were all a long time ago, while I was in my twenties (I'm now in my mid-forties).... (I'm using your distinction between "casual sex" and "one night stands," Arikas.) Even when I was having 'casual sex' those years ago, there was at least some connection and affection. That is, it wasn't just about bumping body parts. (... and, yes, I'm talking about experiences with both sexes, here.)
What's interesting in this orbit is that there seem to be two differing models or mindsets which may be at play. One model/mindset draws a firm line of distinction between something folks sometimes call "just sex" and "relationship" and the other does not. The first kind is digital and either/or, like a light swich which is either off or on. The other is more like a dimmer switch, with dim light, brighter light, yet brigher, and brightest -- a spectrum. I'm much more intrinsically comfortable with the dimmer switch, but still don't have "just sex" (which isn't about connection and relationship). Seems a lot of times when things go awry it is because the two types are talking with one another but not really communicating. A dimmer switch sort of person will typically feel really put off by being treated in the "just sex" manner. That's because his or her feelings are always involved in the ... well, under the sheets. The other type often shuts off these feelings in pure pursuit of ... well, sensations.