Dumbledore's "nobility"

[AbendrothBlutjager]

Is Dumbledore as "noble" as McGonagall says he is?

Somehow I don't think so. I think he might have had a checkered past,
and that the reason he gives people second chances is because he
messed up somehow... and someone gave him a second chance.

Maybe Dippet or a previous headmaster gave him a second chance?

Maybe defeating Grindlewald was Dumbledore's way of making up for
something he once did that he's ashamed of?

Would his "less-than-noble" past have anything to do with whatever he
relives from drinking the green potion in the cave?