how much does a person know you?

Honestly, how do you even measure? Sometimes we get angry for certain actions that we think others did. but what if, they didn't do it? or what if they did it for a reason that is understandable and you would do the same in that situation too. It's easy to say do not judge others. but here's the question: how do you then self-protect if you don't see the person as who they are? well, I don't agree with judging people either and i agree with protecting your heart from people who are not doing you good. what do you do then? my solution: 1. it's better to do what you can and make the best out of the situation. rather being called the "bad person" than feeling guilty right? it's "tagged as bad person" v.s. "lifetime guilt" no definite answer to this solution. but doesn't it makes you wonder?