It's come to this: No one is more willing to talk about acne than a musician.With celebrity acne-fighter Proactiv's signing earlier this month of Justin Beiber as a spokesman, the teen star joins Katty Perry, Arvil Lavign, Jessica Simpson, Alicia Keys and Mandy Moore as recording artists who have signed up to talk openly about "critters on their face," as Perry refers to it in her spot.