To borrow a phrase from Spock, "Most kind."
Well, as I've gotten older and seen the episodes I love 11'ty billion times, I start to appreciate some single examples of acting in the bad eps. Skip Homeier (now out of his Nazi togs), does a nice job, I think, as the obsessed and maddened Dr. Sevrin. I especially like his conversation with Spock when he's (Sevrin) in the brig:
"Because this is poison to me. This stuff you breathe, this stuff you live in, the shields of artificial atmosphere that we have layered about every planet. The programs in those computers that run your ship and your lives for you, they bred what my body carries. That's what your science have done to me. You've infected me. Only the primitives can cleanse me. I cannot purge myself until I am among them. Only their way of living is right. I must go to them. "
You, with a mentally unbalanced William Windom as your avatar
, can surely appreciate a scenery-chewer, even if it's in a bottom-tier ep.