I've never got a bad DIG key personally, but others here would likely have a better opinion than i would, I don't use it as often as most.
I HAVE got a key for a game with the incorrect game title
once that was to some garbage game with an extremely similar name and not the one I thought it was...unfortunately I realized it so late I never got to see how support treated the situation.
One thing I do know for a fact, from people being pissed off about it is that once you mark a key as used on DIG, you have 7 days (iirc) to un-mark that key or its lost forever, even to the website staff itself.
Which is likely why pos was concerned about doing it...but in retro we trust, this whole forum is based on that faith in the boss.
If I was concerned about it I would keep my keys given to the arena in a separate spreadsheet, personally I'm not...what i give to the Arena is for the Arena.
Even if I decided to never come here again, I wouldn't ask for my keys back They're for the users
EDIT:
People have the wrong idea that this is a swap forum, its a sharing forum. if you don't want to share what you give, don't give it in the first place.
Swap as you ask...at least you know your dues are paid if you leave and nobody owes anyone. (for the record pos--this is NOT directed towards you...you have a reason for concern with how much you share)