This has to be so ..... but very few living human beings have encountered pure evil.
All of us as people are ambiguous, and we all express both evil and good - this is just a fact of life. To censor and reject any particular human as evil is very dangerous because each of us also has evil within us and in condemning them we necessarily condemn ourselves. Oh for most of us, the way we express evil within us is not the same as with those who are great amongst us, but that's not a matter of degree, only of type and scope.
Let whoever has not sinned cast the first stone.
For me, it is sufficient to reject whatever is bad in people and embrace whatever is good - the principle not the person. And to always question my own power of discernment of good and evil too, because even at my age I am still a child learning to see between the complexities of what is good and what is evil when they are blended together into each person.