This has been discussed ad-nauseum on several boards. Here's my take on milk - any type, including skim/non-fat:
There are many things that a bodybuilder avoids (or at least "times" within a program*) with their nutrition. *Post-workout is the only time mono-saccharides/simple sugars should be taken (preferably dextrose and/or maltodextrine).
Lactose is nothing but a mono-saccharides/simple sugar and "I believe" should be avoided. There are many others that will argue that milk should not ne used for other reasons as well. MANY people are "lactose intolerant." Wonder why!?!? If "adults" shouldn't be drinking milk, it's no wonder so many are lactose intolerant or get bad gas from lactose.
You can make your own decision, I've made mine. For me, when I drink milk, it makes me look smooth/thick-skinned. Why do you think bodybuilders drop ALL dairy prior to a contest?
xcel