Judgmental is not stating an opinion or even labeling something as "good" or "bad". Being judgmental is when based on one quality of someone or something you conclude about his whole nature, about all his other qualities. You judge his wholeness based on one aspect.
When I was young and negative (lol), I used to judge people by the way they talk, interact, and look. Looking back, I realized why I had been like that: because I am worse than them. Plain and simple.
I was judgmental 'cause I am masking the fact I am an easy target to begin with. I was insecure of my own self that I vent these all out subconsciously to other people I secretly hate because they remind me of how 'miserable' I was.