Most of them I think are terrible. If well executed, they could have some potential, but they never seem to work properly. The one with the "Dolly Llama" thing (a newer episode, forget what it's called at the moment), was by far the worst. Same with the imaginary friend search, that part of the episode "Fifteen," some of them are just plain terrible.

Others, like "The Great Sock Mystery," are ones that are alright. Same with the parts of it from "It Came From Beyond," and even the original "The Secret Life of Dogs and Babies" I like on some level.