I've been in a discussion with my father in law about not being able to remove noise from a very old very bad recording. The noise was at LEAST 50% of the signal. I couldn't explain to him that if you take that away, it just leaves a gigantic hole behind, with all the artifacts around it making it sound even worse. People in general seem to have real issues understanding this concept. They seem to think that if you take something out, it automatically gets filled up with a goodsounding recording of the original instrument...
The weird part is that he is a professional graphic designer, and those guys get a lot of the same crap we do in their job. Just visually. If I would expect anyone to get this concept, it would be him. He's a cool guy though, so it's all good.