a very common refrain from my brother and i, to my mom, when we were growing up, was "this is okay, but don't make it again, ok?"
The closest my father ever came to a criticism was, "Well, I wouldn't order it out...." and we generally didn't see that dish again anytime soon. :)
My husband is the opposite of a picky eater, and I'm glad. We're spending some time in Paris next month, and in THAT city I would certainly hate to see him push uneaten food around his plate....!