Ok lets say player A and B each have 100 chips, and are the 2 blinds. Player C has 5 chips. Player C moves all in and Player A and B both call.


Now there is 15 in the middle which any of the 3 players can win. There is NO sidepot until someone bets. So you cant bluff, well you can but if A bets on a bluff and B folds, A gets nothing unless he beats C as well, who of course can not fold.


Think of betting into a dry pot as betting into an empty pot when a third player is all in and cant fold.


In and of itself it is NOT unethical, although may or may not be the best play. The ethical problems are based on intent.


If I am player A and Player C is a friend of mine, and I bet to get B to fold and increase C's chances of winning, this would be unethical.


If I am player A and SAY to player B, lets just check it down (ie if you dont bet into the dry pot I wont either) this would be collusion and unethical as well.


It is often presumed that players know what they are doing. If the flop came AKQ and A bet holding 3-2 and B folded 77 and C wins the hand with 66, it is going to look as if A was being unethical betting into a dry pot to get B to fold to benefit C. It may have just been an incredibly bonehead play only A really knows.


On the other hand if you have the second nuts or better on the river it is never a mistake (with regard to the all in) to bet into the dry pot. The reason is that if the other live player has you beat the all in is busted anyway, and if the all in has you bested he would have won regardless of your bet.