I noticed that even with 'good looking people', after being with them a while I notice certain angles that make them look less attractive, and sometimes their faces look a bit weird. It doesn't put me off whatsoever, it's just that it makes you realise no one looks perfect 24/7. Also I look different in mirrors, sometimes good, sometimes bad, depending on the light, the type of mirror, what state i'm in etc. So don't base your mood on what you look like in the mirror, and the best way to avoid that is to not look in mirrors too much. I used to notice more of my flaws when I was alwasy staring into mirros, and they used to play on my mind more, making me almost suicidal. After abstaining a while, I actually look better than I remembered lol.
Photographs, that's another thing that either makes you go hmmm I ain't that bad after all, or makes you realise suddenly how bad you look and want to tear it up.