[psandman]

he problem is of cours enot that they check it down, its that each knows that if they can get the other players out of the hand they will not have to risk any further money, the other players do not have the luxury of knowing that there will not be another bet.

That being said I have seen some limit players who will check it down with everyone in the game if it gets to heads up. Either they don't think its "gentlemanly" to bet into one opponent or they think that its not worth the risk to win one additional bet.

If the players are of this variety I would contend its not unethical that they check it down when heads up with any opponent its just bad strategy.