> I would never advocate cheating, but if a
> player managed to hold-out a couple aces and
> then introduce them into a new DD game, they
> could greatly increase their EV. It seems
> like a cheater would be much more likely to
> get away with this sort of thing since there
> isn't a full accounting for all of the cards
> played.

> Also, hole card play would be harder to
> detect (it always looks weird to hit a hard
> 17 vs a 9 up, but it looks more suspect when
> you can confirm that the player only hits
> that hand if the dealer has a 9-A in the
> hole).

This is why the practice was abandoned in Nevada, and more recently in the Californa casinos.

It was supposed to be a counter counter-measure, but it creates all sorts of other problems with game integrity.

Furthermore, it is no real impediment to counting.