Should we discard achievements made by unlikable people?

[Martian Mermaid]

Every single person on this planet has done something beneficial as well as something negative to other humans. Usually, the pros outweigh the cons, or the pros are equal to the cons. In these cases, we do not tell them their good deeds don't count, instead we greatly appreciate that someone has done the good thing.
We should do the same for everyone. I mean, surely, if it is discovered in their lifetime, throw the person in jail. But are we so petty to believe that we should disregard that something beneficial has been done, just because of who did it? Or should we let it continue to benefit us?
Aren't we better off appreciating what we have, no matter where it came from, so long as it no longer hurts us?
My father isn't the nicest guy. He used to be a mean drunk(he stopped drinking now) and he cheated on my mother. But I still use the Christmas presents he bought me. I still appreciate that he's provided me with a sister. I am not going to ignore the good things just because they come from someone whose bad outweighs good.
I almost don't care where good things come from. I just like that they are good.