Sometimes when I start my X there's an annoying squeaking coming from the belt. When I get it wet enough the sound stops. Mechanics have said the belt is fine, so what can be done to stop this sound? Can the spindles (or whatever they're called, the round things that spin the belt) be lubed?

Check your idler pully, mine died at about 80K miles and was squealing like a mother. Matter of fact, take the belt off and turn the pullys by hand, if they squeal at all or don't turn smoothly you need to replace that pully.