Allergies?
I have always heard that eating chocolate can cause pimples. There
were various explanations for this, i.e. acid, fat, etc, and I never
believed it; but I have milk allergies, and while I do drink milk, I
find that my pimples are much tamer when I don’t. Perhaps, in this
sense, chocolate IS bad for acne, since it has milk in it!
Just a comment! 
~Willowbirch