I'm surprised at this, since housekeeping is a non-tipped position at Disney, and they always take what I leave LOL!
I'm not sure on Housekeeping, they may be a higher paid tipped position. The thing with them, you're not usually in the room when they receive the money and when you're gone for the week, they can't exactly refuse.
I used to deliver groceries from the merchandise stores to the villas at the BW. The guests usually would try to tip us for the service we provided, but we were not allowed to accept.