Don't think like that... I know I do the same thing, and it's not really a good thing to do. A lot of artists are a lot harder on themselves than on others. Also, they have an idea of what they were trying to achieve, and if it falls short, that's where the self-deprecation comes from, I think. It's hard to balance not being arrogant, and not being self-derisive to the point where it's discouraging to others. Anyway, just my thoughts... hope it makes some sense.