Is it normal that people judge lightly?

Not every hooligan is an asshole and not every princess is innocent.

So I don't understand why it always comes to situations where someone who looks like he's only doing shit or who has maybe made a few mistakes from time to time is always the culprit.
And someone who has never attracted attention, apart from perhaps making a few derogatory comments, gets the free kick?
It's like in the movies. If you've never watched a typical movie, you're also always fooled into thinking that the obviously "evil" one is the problem, and then later it's the sunny boy or some blonde chick who's jealous.
Why can't some people just look at the situation first without reading anything negative into people they don't know?! It doesn't make sense to me.