I haven't seen it mentioned yet, but 'Try and Catch Me' is my favorite episode (it has everything: the car, Dog, and IMHO, the best "villain"), and addresses the kindness:
> Abigail Mitchell: I'm beginning to be very fond of you, Lieutenant. I think you're a very kind man.
> Lt. Columbo: Don't count on that, Miss Mitchell. Don't count on it.
> Abigail Mitchell: I'm beginning to be very fond of you, Lieutenant. I think you're a very kind man.
> Lt. Columbo: Don't count on that, Miss Mitchell. Don't count on it.
https://www.imdb.com/title/tt0075866/quotes/