Okay, so you’re at the blackjack table minding your own business when you happen to notice something: The dealer has a nine as his hole card. You weren’t trying to peak, but as the dealer placed his hole card face down on the table, he exposed it in a way that allowed you to see its value. Now what should you do? Can you use that knowledge to your advantage?
That question has two completely different implied questions. The first is “is it immoral to use that knowledge to my advantage?” The second question is “is is cheating to take advantage of that knowledge?” The first question I won’t cover because that’s up to you to decide. You may think that you should pretend you didn’t see anything or, if the dealer does it more than once, that you should inform him or someone else working for the casino that the dealer is being sloppy. Or you may think that it’s his and the casino’s loss if he’s going to make a mistake. Why should it bother you?
The second question is easier to answer, though. If you did nothing to aid in seeing the dealer’s hole card, it is not cheating. If you used a mirror, a spotter, a camera or anything like that to spy on the dealer’s cards then yes, that is cheating and it is illegal. If, however, you are simply minding your own business and through no effort on your part you accidentally see the dealer’s hole card, you have done nothing wrong. Using that knowledge to make your decisions is perfectly legal and it is the dealer’s responsibility to make sure his hole card is a secret, not yours.
How should you react to knowledge of the dealer’s hole card? That depends. If you want to take advantage of it, that could mean deviating from basic strategy, since that strategy is for when you don’t know the dealer’s hole card but assume it has a good probability of being a ten. If it turns out to be a two, of course, that changes things considerably. Whatever the dealer’s hole card is, you should think about what total he has and what his chances are of busting with that hand. Also, if he has a hand of 17 or more and you have the hand beaten, obviously you would stand.
If the dealer is sloppy and repeatedly exposes his hole card, you need to be careful how you respond to that knowledge. If you deviate from basic strategy too often and have good results each time, that will set off a red flag. The dealer, the pit boss, or someone monitoring the eye in the sky might think you are cheating. If you convince them that you are not cheating, that you can simply see the dealer’s hole card, you have killed the golden goose. The dealer will either correct the problem so you can no longer see the card or will be fired. In either case, your advantage is gone. For that reason, you should only deviate from basic strategy in subtle ways. Hitting your 19 because you can see that the dealer has 20, for example, would not be a wise decision.