This thread http://www.marksdailyapple.com/forum/thread94865.html has a link to a literature review that describes the evidence for a link between acne and diet. It's a bit short of "the truth", but I think it offers some interesting things to think about. If you don't mind reading your science text books, you can probably read the article and get most of the information from it.
I think you should be really encouraged that your acne responded to a raw diet. That means your diet is affecting your skin and you may be able to figure out how. Did you experiment with adding cooked animal protein/fat to your raw diet and see if you could find a hybrid diet that worked better for your over all health and sanity?
My 15yo DD had acne bad enough that I reluctantly let the Dr put her on oral antibiotic. It was the only thing that seemed to work and she was in danger of suffering permanent scarring on her cheeks. Then last spring she decided to go "low carb", which really was just replacing her wheaty snacks with fruits and vegetables, cereal with scrambled eggs, and sandwiches with salads plus meat. The inflamed, pus-filled sores were completely gone in a month. We're not sure if it's the big increase in fruits and vegetables (veggies are raw and cooked, fruits almost all raw) or the drastic reduction in gluten in her diet. She still eats what she likes at parties or when her teammates bring cupcakes to practice or stuff like that, but the majority of her daily diet is grain free and high in fruits, veggies and animal protein. And she's so much happier with the way she looks.
CW-125, part calorie counting, part transition to primal
GW- Goals are no longer weight-related