I guess it depends on our relation to fanfic as well; I'm sure my book will get a lot more scrutiny, but my fanfic is what I do when I'm supposed to be trying to become "professional," so I don't feel I can really spend (waste?) lots of time on it.

This is not to say that ff is a waste, or that I consider it such. I certainly spend enough time reading it! But ff writing is, for me, always a form of crack.