People typically believe themselves to be "above average" at many everyday tasks. Very rare to hear "I think I'm a little worse driver than average," no?
I find judging people or rating them a subconscious activity. I guess I'd say I'm surprised by the number of people who are incredibly eager to place new people into one of many stereotypical categories.
"What'd you think of Steve?"
"What a hippy!"
Sure, even I do this but I'm not eager about it, I lean much further towards neutrality until proven beyond a doubt by their actions. Stereotyping for memory's sake vs negative stereotyping I guess. A simpler way to put this thought is, I
try to judge actions rather than people. I say try because if some SUV cuts me off I'm quite quick to stereotype them as a "fucking suv driver"
In terms of seriously mocking people (i.e. not when messing around with close friends), I've found this behavior is usually a sign of self-deficiency.
Also, try to keep in mind intelligence has many different forms. I work with people all the time who label themselves as "stupid" when using computers, when in fact they're just ignorant. We're all tremendously ignorant about a amazing number of subjects, ain't nuthin' wrong with that! Very odd to witness people so incredibly talented at what their type of intelligence is best at degrade themselves for no good reason.