A person who has a counterfeit meld or count rarely does so on purpose, and most of the time it was an accident and he truly believe in what he had.
For example, a player declaring gin puts down a hand which he believes is the correct hand, such as:
3♠, 3♣, 3♥, 7♠, 7♦, 7♥, 10♦, J♦, Q♦, K♦
However instead of the Q♦, the player has a Q♥. The error was an accident and he honestly believed he had a gin hand. Although again, it is rare, it does happen. Unfortunately such situations are at times deliberate, even so far as to have the Q♥ laying in such a manner that everything is covered except the red Queen. Your only protection in either case is a careful examination of your opponent’s hands when laid down.
In a partnership game, the partners also have the privilege of examining your opponent’s hand and calling attention to any discrepancies. Keep in mind that, in a singles game, a hand is considered dead once the loser has acknowledged his loss and the cards are picked up and reshuffled, even if a discrepancy is recalled after that. However, in a partnership game, the hand is considered dead when the same condition occurs if it is the last hand being played in a partnership group. Though, if it is not the last hand, the hand is considered dead when one of the other teams has made a play against the specific score that has been acknowledged in a completed hand. If any discrepancy in that hand is subsequently discovered, such as a false run or false knock, the score that had been established stands.
Frequently, after losing their hands, some players have the habit of just stating the number of points lost and then pushing their hands together and throwing them into the deck. This practice is wrong since the rules of gin rummy clearly state that a losing player must open his hand completely to the winner and the winner has the right to verify the actual losing count. In a partnership game, the partners of the winning player also have the right to verify the losing count of his opponent.
When counting an opponent’s losing points, make certain that you are seeing his complete hand and that he is not trying to pull the hidden card trick. That is, sometimes a player will very casually place a down card directly behind another one so that you would actually be counting only nine cards rather than ten. In this manner, he can frequently conceal an unmatched high card. Therefore, always verify that you are looking at a full hand. It is always the responsibility of every player to carefully examine his opponent’s hand when looking at either a winning or losing hand.