Well, maybe I'm a bit of a stickler about those genres. I'm a big fan of both and find them so incredibly different that it seems impossible to mix them up. I'll grant that you're right about some authors trying to mix the two, but even then, the characteristics themselves are quite distinct.

However, fiction is definitely my preference. I suppose that if I were pressed to sort non-fiction literature, I'd have a few problems too. I like to think I'd do a decent job though ;)