What is it about judging you that makes me feel so good? It's really pretty simple: I get to feel better about who I am by beating the hell out of who you are. I'm scared and resentful. I'm angry, arrogant and uncomfortable. And I want relief!
By not assuming that your initial thought about something is truth, it allows you to consider potential alternatives that explain an appearance or behavior. Therefore, you should give people the benefit of the doubt.
I've always believed that I am one of the least judgmental people to exist on this planet; I'd swear to it in a court of law. But alas, during a day at the beach last week with my best friends and their significant others, I saw myself in a different light.