cry havoc

Strictly speaking, I would consider you outside the area of people to be polled, then, because the issue isn't what inspires in general, but what inspires specifically fanfic -- or in this case, what de-inspires it. That said, I'm in the same boat as you, seeing as how I almost never write fanfic now, and only do so once in a blue moon as I take a rather belabored approach to finishing up a single outstanding long-term fanfic. Otherwise, all my fanfic ideas quickly transmute into ofic ideas, with no exceptions. So for me to answer the question, I had to think of when I was writing fanfic regularly -- and what would cause me to ditch a fic idea.