A friend of mine once advanced the theory
that the reason we pick fault
s with our own looks is because
we are only able to see
ourselves in parts.
As push rightly points out, it is impossible for us to get a proper look at ourselves because of field of vision limitations. This is what makes us look at different parts of our face separately, and because we're incapable of constructing a coherent picture, we seem somehow distorted and unreal.
When looking at other people, we see more of the whole, which is why we're alwasy suprised when they hate their own looks or a photo of themselves we think represents them perfectly. It's half psychology, but half optics, too.