The psychological reason to this is because no one else looks at nor judges your pictures they same way that you do. You are your own worse critic is a common saying. If you were to even scan over other peoples photos with a fine tooth comb and a magnifying glass, you would not notice the imperfections and problems you find with your own. You see, you have to live with yourself and see your self so much, that you train yourself into finding faults. When we comb are hair, wash our face, shave, put on make up, we are in a sense studying ourselves and noticing imperfections. That is the whole entire reason for the mirrors existence. We do it so much that it is the only reason we look in the mirror. Every time we do, it is like having a beauty contest with only one contestant and one judge.Chances are, you are the only person who would think such a thing of your photos where others would think you looked nice.

Source: Why does everybody look good in pictures except me? – Quora