I suppose there are no "good" or "bad" people. There are only people who commit "good" and "bad" acts. It's the actions of people that we judge.
And good and bad are relative terms, they are not "absolute" except maybe in some far off land of abstractions. Everything in our realm seems malleable or situational.
Lying, cheating, stealing, murder are all "bad" acts, but then you could think up scenarios where lying, cheating, stealing and even murder might be "justified" or at least "understandable."
Still, I do think we know what's "good," it might actually be built into us, and most of us do have some concept of conscience. But then again our powers of self-justification and self-delusion are remarkable.
Sometimes it's easy to see when someone else goes off the ranch. Then again, as they say, "don't throw stones if you get stoned," or something to that effect. We are all both judge and jury of our own realms. It seems some of us are hanging judges when it comes to others, and supremely understanding and compassionate judges when it comes to ourselves.
Double standard to the max.