Oh God I hope it's the mirror! Although what you see in a mirror is backwards, so it's not going to be the same as what other people see (although faces are fairly symmetrical so not a million miles away). I can think I look really good in the mirror, then I'll see a picture of myself taken on the same day/night and look absolutely awful!
I wasnt ever 'photogenic' but pre digital I was quite pretty in photos albeit with my eyes shut or whatever. Then I thought something had happened to my face because I now look awful in pictures. But then I saw a video...and look just like I used to on film! It's bizarre. Also saw pics from a friends wedding taken on slr (?) camera and look great on them, they were just candids I was in background of. Blame digital! I know what a pp meant about everyone else looking like they look, it's rubbish.