Okay this one is something of a blackjack myth, but it does have an impact on your blackjack odds.
Players tend to believe that when the dealer deals himself a 5 or 6 up that they are sure to win. They know that 5s and 6s are the weakest up cards for the dealer to have in blackjack. So they will automatically begin counting up the money they are sure is coming their way.
However, those 5s and 6s are not quite as much of a sure thing as you might think they are. In fact the dealer has less than a 50% chance of busting with those up cards. With a 5 showing the dealer only has a 41.8% chance of busting. And with a 6 up he only stands a 42.3% chance of busting.
So how does this translate to blackjack odds?
Well the dealer has to play until he can stand on a hard 17 and higher or until he busts. He will not finish with a 16 or below like a player can. So there are chances for him to win:
5 up:
12.2% on 17
12.2% on 18
11.8% on 19
11.2% on 20
10.8% on 21
6 up:
16.6% on 17
10.6% on 18
10.6% on 19
10.2% on 20
9.7% on 21
Any one of those other outcomes could happen. And they all mean that you could lose, giving the dealer a 58.2% or 57.7% chance of winning respectively.
Typically when the dealer is showing a 5 or 6 the player is holding a stiff hand. In those cases we are hoping for the dealer to bust. But as you can see, he has a better shot of winning in total than he does in losing. Which means that your blackjack odds of winning are not as high as this blackjack myth leads players to believe.
This does not mean that players should feel any less for a 5 or 6 up card. It still remains that the dealer has the highest chance of busting in blackjack with a 5 or 6 showing. This only means that players