When we are extremely critical of others, the voice that pops up in your mind telling you "That is totally worthless, average, not good enough, just decent etc." would get strengthened with each reinforcement. Once its totally reinforced, you cannot suddenly turn it off, esp when you are dealing with yourself. You could deny that nothing applies to you, have clear double standards, generate elaborate logical explanations etc. but you cannot fool yourself at a deeper level. The very fact that you have those ridiculously high benchmarks of what is considered ideal in every department will trigger a comparison each time you achieve or do anything. So with this comparison happening, all your achievements would appear meek in front of these crazy standards. So in effect, you would be getting very little reward because you've created extremely large trenches to fill.
Infact even while gossiping(usually bitching about people) the person indulging in it gets pleasure due to the sense of 'moral superiority' their ego feels. Even the simple fact of sharing a news provides pleasure to the person sharing because at that point of time this person knows more and therefore enjoys a certain 'knowledge superiority'. In other words this is a different strategy to do the same thing, feel superior. When you put down everyone around you, you automatically become superior in comparison.
I don't think the concept of double standards really exists beyond our rational thinking mind. Our reward centers hardly work by this kind of mind anyway. I think real truth is what we should always be aware of. Avoiding or masking that just messes up your reward system, the reason for all your activities. Sometimes I feel, why beat around the bush, why cant we concentrate of lifting ourselves up instead of trying to belittle everything around us. It essentially does the same thing in a more efficient way?