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.
"I had no idea you were so... formidable. " - Anan 7 to James T. Kirk, A Taste of Armageddon