I've bought SPT's from a coin dealer who bought them at spot 1oz silver, had them for sale at face value. While looking through what he had in his display case in his store, I commented on how some had tarnish brass outer rings. He said "no problem." He took them out of plastic holder, dipped them in a liquid that removed the tarnish, dried them off, and put them back in the holders. I said "cool", and bought them! This coin dealer was savy enough to know that casino collectors don't care if a chip or token has been cleaned. Too bad the slabbers still haven't figured it out.

Bob