There are a lot of creatures that have very distinct smells but you never get close enough to them to notice. Reptiles make for some stanky pets even though I doubt many of you could identify a lizard terrarium smell. Many insects produce smells as defense mechanisms but you can barely smell it as a human. Grasshoppers and many beatles in particular tend to secrete nasty smelling slime when handled, a smell that follows them around, and that's a smell I can recall clearly and sharply.

I have a theory though that human smell has lost sensitivity because of social reasons. We used to be fantastic at chemical analysis until civilization happened and we all started using soap and telling each other that normal, every day smells are now "bad" and we need to mask them with perfumes and soaps. This made us afraid to smell things for fear that we were taking something "bad" inside us, the idea of evil or bad air goes back very, very far.