Also as protection against marked cards, another subtle aid is the regular check of the deck to ensure there are no marked cards.

This can be accomplished throughout regular deal, by keeping an eye on one's own cards and deadwood (which shouldn't arouse too much suspicion). A card marked well enough will be difficult to spot, but crimps and major shading should be noticeable.

One trick is to check the entire deck at one's deal. By picking up the cards, and flipping through the corners like an old picture book, one should be able to spot crimps and markings. Done on all four corners and done perceptively enough will indicate that there are no noticeable markings on any of the four corners.

Noticing players overly concerned with looking at the backs of other players' cards is another obvious protection.