Human behaviour is unique in many ways unlike other living beings.
One of them is "being judgemental"!
I am not sure what behaviour theorists say about this, I would certainly like to share my point of view based on my past experience or call it being judgemental ;-)
Fundamental question; is being judgemental bad?
I don't have an answer. But, I guess most are judgemental at times about people.
One of the most common reasons could be "believing someone's view/opinion" about an individual or a group.