Why owl pellets not stink?

Answer 1

Because they are, even though regurgitated, just bones and fur and scales which, bones, never smell as skin and meat and other sources of protein do, with the exception of insects. The scales may sometimes begin to smell if the gizzard (where owls filter the meat from the fur and bones) has not properly taken the meat off, as the same with the bones and fur. This occurrence is rare but with some luck you may have found yourself a vile-smelling house.