Honor thy Father and thy Mother?

What happens if according to the definition that your mother and father are not honor'able'? what are you supposed to do then? What if my dad was adolf hitler...should I honor him? what if my mother was cleopatra should i honor her? what if they are fukced up bad parents, why should i honor what is bad? What is God? God is Good right? God wants us to worship Him, and he is Good, so wouldn't honoring a bad parent (who is similar to evil adolf Hitler, or witch cleopatra) the same thing as honoring evil? Why would God want that?