All ethics, decency, courtesy and fairness falls out of the Golden Rule - "Treat others as you would like to be treated". So the question is what happens when we are all those things, for the best of our ability, but we get treated poorly by a narcissist that abuses our kindness. Do we the embrace the psychology of our abuser and accept that is how the world is and that it was OUR fault for being naive?
These rules are the revenge fantasy of a wounded child archetype. They are highly dysfunctional in any healthy community, relationship, friendships of family. If you practice them, you will end up losing the most valuable of friendships and other relationships that would have helped you out the most in life, and keep you in that hell.
If you want to be able to recognize psychopathic indicators in others, read up some books on modern psychology that addresses that directly. It is not very hard to recognize such people.
I heard this is the most popular book ordered in US prisons. That should tell you something.