Judgmental People

One of the more difficult things to actually grasp about narcissism for many is the reason they treat certain people like they're less important, or unimportant: they actually BELIEVE that the person IS less important than themselves, or unimportant to the human race and the world.
When they criticize or belittle a target for random things like how you wear your hair, how you spend your time, the job you have, the interests and ambitions you have, your education, your friends, your capability, your intelligence, and your mental stability, they're SERIOUS! They actually believe what is coming out of their mouth, much of the time. It's true, sometimes abusers will say mean things on purpose for the sole purpose of causing injury, but quite a lot of the time a Narcissist is dead serious about whatever he or she just said to you and about you.
Since one of the main problems that comes with narcissism is fantasy overlaying reality, a person with this disorder simply believes whatever their imagination tells them.
So if they see your dirty truck, their imagination might make up a reason for it, like "She's a lazy person, that's why the truck is dirty" or "He's a slob, he doesn't even wash his truck when he goes through mud puddles".
They don't have the capacity to think "Hey I don't know why that truck is dirty". They also, more importantly, don't have the capacity to see a dirty truck and THINK NOTHING about it, or transfer judgment onto the truck owner. EVERYTHING has to have a judgment, a "good" or "bad" assessment. Everything about another person HAS TO fall into a "good" or "bad" category, that's all they have.
There isn't even a neutral zone or a funny zone, like "Joe is so funny, he doesn't care what people think about his truck being dirty" or "I wish I was more like him, not caring what people think" or even "Oh neat, looks like Jane was 4-Wheeling with her truck again! I wonder if she went camping?"
There's no time where they wouldn't NOTICE anything they think is fodder for judgment. The ONLY time they will think with neutrality, understanding, or admiration about another person is if they have the person on a PEDESTAL. THEN the person can do NO WRONG... until of course they "fall off" the pedestal, and then it's back again to judging negatively.