What you need to do is learn some new criteria by which to judge things.
What we've learned most recently is what looms largest in our minds. If you've just really finally figured out white balance, you're going to be hating everyone else's white balance. If you're just mastered single point AF and which eye to focus on, you're going to hate every portrait you see. If you find yourself nitpicking the technical stuff in everyone else's pictures, go spend some time learning about color or composition or drawing. If you find yourself nitpicking everyone else's visual balance and use of chiaroscuro, spend some time (re?)-learning about some technical trivia.
Eventually it evens out and you stop nitpicking altogether because you have a kind of gestalt view to critique from. You'll start to see the good and the bad in everything, and it becomes just a newer and more interesting way of looking at pictures.