I don't like to think of people as immutably good or bad, but I get what you meant.

There's a bunch of factors.

• are they honest?
• are they kind?
• do they care about things other than themselves?
• do they try to make the world better?

So, someone who lies, is cruel, doesn't care about anyone else, and leaves the world a mess is being a pretty bad person.

Someone who just keeps their head down, goes to work, and is polite to people they meet is kind of middling.