I think that photogenic people and performers, apart from being physically attractive, are really good at "seeing" themselves.

I'm not sure I agree with this--or rather, I'm not sure this is the best model of what's going on. My impression has always been (and this fits with my photo-taking advice elsewhere in this thread) that you don't learn to see how you look when you're doing something right--you learn how it feels to be in the correct position to do it. That is, someone who's watching you might say "your back is curved, straighten it," and you can straighten it, but you still don't see what they see. You just find out what it feels like to have a straight back, and can try for that again later. I've never played golf, but I'd be surprised if good golfers are thinking about what they look like when they're putting. I'd expect them instead to recognize the feeling of being in the correct posture from having done it before.