I guess it's more of a function of their speed Erik, when I think about it. The skin shedding thing was cited as the main reason they stay clean by a naturalist I knew during the whaling years. However, after contemplating it, I never did notice great amounts of barnacles on the faster filter-feeders- finbacks, sei whales, and minkes. But then again, close encounters w/ those animals are fairly rare.
Further contemplation led me to beleive that the humpbacks (which I spnet the most time in close quarters w/) had most of the barnacles in dead-water areas, like around the rostrum, cutwater, tailstock. Dolphins and other fater whales are evolved extensively to provide a highly streamlined body form, w/ little or no dead spots. In fact, the benefit of the high rate of skin shedding is believed to eliminate potential vortices and drag during fast swimming.
Right whales bodies,in fact, have excessive skin folds on their head, along w/ callosities (growths of hard skin), whose purpose seems to be to actually encourage the growth of barnacles and other parasites, to create unique patterns, potentially for individual identification. And, by the by, Norm, their testicles are the size of VWs.