"By Any Other Name" has a similar theme as "Return to Tomorrow," and is probably more campy throughout. However, it's also more effective overall, because it picks a tone and sticks with it, rather than throwing the book out the window when the end rolls around.
The theme is "alien lifeform takes human form and is intrigued by human sensation." Once all but four Enterprise crew members (Kirk, Spock, Bones, Scotty) are temporarily disabled, this leaves our four heroes with the task of undermining the Kelvans, each with a special trick suited to their personality. Kirk distracts the female Kelvan with the wonders of love. Bones injects his subject with a drug that makes him irritable. Scotty gets his subject drunk through a sequence of amusing drinking scenes. Meanwhile, the leader of the Kelvans watches all his people fall apart while Kirk wooing the female sends him into a rage of jealousy.
This is all fairly silly, but the episode knows it's silly. Marc Daniels applies a deft light touch to the material that balances the threat with a keen sense of humor that constantly reminds us not to take any of it too seriously. The end result is surprisingly likable and entertaining—probably better than it has any right to be.