Flea Eggs, picked up from John's Sweater
The fleas are all over the cat, who will scratch and bite if I approach with the flea comb.
I'm not even considering a bath and shampoo!
I guess you can clicker-train moggies to put up with almost anything, but this one will sniff and dither before deigning to accept a treat. Not like a dog who swallows everything on sight.
Oh, and he doesn't like raw chicken. Only crunchy junk-food pellets.