Ya, those kitties seem to get a nip-on to some of our groovy way-out human smells, ya gotta wonder. Doggies groove too of course, they're just more matter-of-fact about it in a Viagra vs. LSD sorta way.
My sister's cat goes gonzo over my shoes in the same way. She has never collapsed like the kitty in the photo, but she dives right in there and starts rolling around. I'm glad someone finds my foot odor attractive.