Hmmm sweat I thought about that too, but I dont seem to sweat so much when I play. Well I can understand strings getting rusty because of sweat, but I don't think sweat getting down to the pickups (well ..yet). I was thinking the environment I'm in, has lost of moisture in the air?? (Dont' know if that makes any sense but). Do any of those guitar cleaners work on pickups too???