Calcium deposit, deteriorating contact for slots including memory. Why didn't you use electronic contact cleaner again? Wanted to save few bucks to hand someone a board that just isn't going to last as long as it should have? Oxidization of copper is real and once you put water on it it just happens much more rapidly. Unless you dried it above boiling point of water, you still have water molecule attached to copper no matter what you did. The board is going to look like in less than few months. I suggest just keeping it for your backup instead of risking someone else with it. If I personally received a product like that and found out such cleaning method was used was not mentioned, I would felt it was fradulent transaction on my end.