CHOCOLATE:
Acne is a genetic issue at its core.
My son went to bed in January 08 with a couple of minor zits and woke up with a chin covered in acne. Over the next few days it spread up his face and I called the dermo. A month and a half later(it takes forever to get in) the doctor diagnosed him with deep scarring acne before he had even crossed the exam room to the table. It was that bad. Acutane and cortisone shots for scarring were his only options. According to the doc, diet, nor lack of cleanliness is ever the cause of true acne. It is 100% genetic and inescapable.

Now, a nasty zit here or there may be caused by diet but you cannot blame true acne on the unlucky sufferer's habits.