I think of it this way, if you crack a book out and then try to sell it, you KNOW no one gives a F if you show the deslabbed label with the book. That grade along with any other former grades (even hand written on a backing board by a reputable dealer) is considered useless to 99% of buyers. That said, the rules of the game dictate the reverse for the seller.
That said, if the buyer asks for info and finds out the answer given is a lie, then they’re untrustworthy and accepts and should expect exposure.
I think if we as a community expect 100% disclosure of former grades from dealers, then we should expect former cgc grades to be printed on the label as well. Now wouldn’t that be something?