It wasn't clear from what I found online-but I'm assuming that it's kitty litter soiled with urine that allegedly deters them?

Not that the other feline waste material is pleasant. With several dogs, a pet bird and a horse, I'm no stranger to poop-scooping. However, the litter box makes me gag and DBF-who wanted to keep this stray kitten 5 years ago-conveniently forgets to clean it.