It's like a Supreme Court justice once said of obscenity (someone will know who this was, I don't feel like looking it up,) "I can't define it, but I know it when I see it."
That's less true of "fine" art than obscenity, I think, but the definition of "art for the sole purpose of display, not applied art" makes good sense to me.
I agree to avoid the term. The real problem with using this as a descriptive term for one's own work is that "fine" implies excellent quality in most people's minds, even though it isn't meant that way in this term. There ought to be a value-neutral term meaning "art solely for display." Then again, there is - art. Various "applied art" are sub-categories, and if isn't any of those, it's just art. Maybe.