I've noticed that there is a lot of talk about Dummbledore's past and what kind of person he truly was. My question is: does it matter what someones past is or who they are in the present? Dumbledore is supposed to have some dark past filled with secrets and lies. Even if that is what he was, think about who he became. Dumbledore was a wise and brilliant man. It doesn't matter if someone was a bad person back in the day. If they are now someone who can tell you wrong from right and control themselves that is who you are supposed to judge.
Take Robert Downey Jr. for example. He used to be a raging addict and now he has been clean for a number of years. It's easy to do bad things in your life and it's also easy to do good things in your life. The part that is difficult is redeeming yourself after you've done bad things. In order to judge someone, no one should look at who the person was in the past. The person must be judged now that they are a brand new person.
Snape was always considered a bad character in the Harry Potter book series, and then you learn about his past. This does contradict my earlier statements and I realize that. If you look at someone and think they are a bad person their past should also be checked out. To be fair, I have to say that past can trump present. Snape had every right to be resenful of Harry. His father was a jerk to him and stole his one true love on top of that. So all in all, it can be ufair to judge someone based on theirpast but if that past has hardships, I believe second chances are due.