This one happened on a chair massage gig and it really isn't that funny, but there's a lesson to be learned.
I was working on someones shoulders during the chair massage when I realized I was rubbing the color off her sweater. Yep, turns out the stuff I was using either to sanitize my hands or clean the face cradle (I think it was the cleaner) was taking the color off her clothes. I'd to give her money to replace the sweater.
Lesson to be learned: check your hands and make sure you've no cleaning materials on them before starting a new client. Also, check the hand sanitizer to make sure it won't remove coloring from clothes.