There is no black and white for the most part when it comes to people. We all reside in the gray area for the most part. Though I think it is easy to point out those who are definitely more of a black area inhabitants.
Think serial killers who personally killed multiple people and those in power that caused deaths of millions of people like Hitler or Putin.
For some reason it is harder to identify those who reside in the white spectrum. I guess those who work for charity or donate most of their money? I don't really know, I know that I am firmly in the gray zone and I am OK with it.
This phrasing made me laugh. :D
But yes, there is a spectrum of good to bad, at least based on social order and convention - and when people are intentionally harming others, well - it is pretty obvious.
I wonder if it is harder because we become more blind to them, making assumptions about the kind of person they are, based on the position in society they hold. Look at the many "god-fearing" people who abuse children who trust them.