Re: most "wrong" episode...
To me there are a few TOS episodes. Omega Glory comes to mind. The savage "Yangs" (who are white) that love freedom and the "Kohms" (of Asian descent) are oppressed.
I'm not sure that was the intent, more about giving the audience something they easily recognize.
"If I hadn't tried, the cost would have been my soul." - Admiral James T. Kirk, Star Trek III: The Search for Spock