This is on going debate that has been around for quite some time. How can a card be altered if it has been returned to its original condition? There is a company "Gone with the Stain" that has been in business for at least 15 years and they have a continuous stream of cards that come their way.
The issues I believe was if any chemicals were used. That would make it 'altered'.
Of course theres discussions whether 'soaking' is permitted.
I feel as long its water, it be fine. I mean its your business if you stain the card or warp it or whatever to remove residue or paper stuck.
Yeah I agree, bringing back to what it was, but the key word I use is, was it by a chemical?