Monsters in DFRPG follow their instincts. They don't have instincts to hide their kills. It literally never occurs to them that it could be a problem. (Just as humans don't worry about all the stray hair, etc. that could be used for shapechanging, spells, etc.)
Now, warlocks can think of such things. Except I doubt the normal inhabitants of the Never-Never really appreciate being used as a dumping site for bodies (or anything else). Imagine the scene where a warlock is trying to convince the police that he has no idea about all those missing people, and a group of fae show up with body parts; "Excuse me, but I think these belong to you..."
Make a contract with the local ghoul population; it's easier.