[AlexanderHowl]

Yes, you could have a supernatural creature with an Uncontrollable Appetite for human feces, though I would suggest having other traits as well (Bad Smell and Odious Personal Habit at a minimum). Such a creature might harm people indirectly through spreading diseases and parasites, but they would probably not directly harm people. In fact, it might avoid them, as it may feel disgusted by its uncontrollable appetite.