perfection?

It's been pointed out to me recently that I compare people and that it's something I shouldn't do. Because people are just different.. and there's that thing from the wear sunscreen speech, where they say that you shouldn't compare yourself to anyone else, "sometimes you're ahead, sometimes you're behind, the race is long, and in the end, it's only with yourself".

That's the theory. In real life, whenever I see someone that I don't like, doing something that bothers me or that's just plain stupid, he pops into my mind. This would be a good time to mention  this tendency of mine to idealise my object of affection.
I keep thinking in black and white, write or wrong, even though I'd rather be able to just take things as they are and as they come. What could I do to change my mindset and be more tolerant?

Later edit (and PS) - The glass house is a wish for the future, it looks so inviting..  (found it in lolita's beautiful blog.)