Took my two babes to the vet last night, as I noticed one had what appeared to be acne about two weeks ago....and then checked the other cat on the weekend and he is showing early stages of it too!
My cats have never eaten out of plastic bowls, always china ones, which I clean in the dishwasher.
First of all the vet (over the phone) got me to try Betadine from the drug store. Turns out it is an iodine solution which can be bought over the counter and is good for scratches etc...to prevent infection.
However, my female cat's acne was quite advanced and it bled everytime I dabbed the iodine on her, so I hated doing that.
Anyway, went to the vet after the weekend and they are both on antibiotics.
It is possible that they are reacting to some new cleaner that I am using (cleaned all the rugs), as the vet can't think of anything else obvious.
The acne is quite dry looking, not too many ruptured pimples...and has black flecks which are possibly dried blood.
Once the acne dries up completely the vet suggested that I wash their chins with a little soap and water from time to time just to help them keep it clean as it is the hardest place for them to keep clean.