It's like you might have some great scene that you love but for some reason - and you can't necessarily put your finger on it - the movie's not working or it seems slow or ponderous in some way, and even though it has your favorite scene in there, actually the favorite scene is the culprit. That's the painful thing about editing, is trying to locate those things that are holding the movie back and then having the guts to cut them. And it is painful to do it.