Btw.. I found one of the best cures or remedies for feline acne. Tea tree oil facial wash from the body shop. It doesn't say its safe for pets, but a) since she's not washing under her chin well anyway and b) I washed her chin off afterwards with a safe soap, I figured.it would be fine, and she has been.
That black debris on her chin all but disappeared after the first washing. It came back slightly, so I washed it again, and its totally gone. Washing alone just wasn't cutting it, but with the tea tree facial wash, it pretty much jumped off her chin. it was amazing!!