What can cheaters do with honest equipment? More things than you want to
know about. Here are a couple of examples:
1) Along the lines of your example, it is not necessary to manipulate the
dice under the table to have an advantage. A player can shake the dice,
and then before rolling take a quick peek in the cup to see if the dice
are positioned favorably (i.e. if he needs to hit an ace shot, he wants
to see a six facing up). If there is a six facing up he can throw the
dice the way you say making it likely that the dice won't roll and the
ace will remain on top. If there isn't a six facing up he just gives a
normal roll. Not a lock, but it does increase his odds a lot.
2) If a player can anticipate what number he is likely to need for his
next roll (for example he is on the bar against a 5-point board), when he
picks up his dice he can do the following: Instead of dropping them both
in the cup, drop one in the cup and hold the other between two of his
fingers, picking up the dice so the number he will need is positioned
appropriately. When he shakes the dice, you hear the dice clicking
together, so it doesn't sound suspicious. When he rolls the dice he just
lets the die he was holding in his hand slide out, and the number he
wants will be right there. A good dice mechanic can do this right under
your nose and you won't spot a thing.
These are just a couple of examples. There are several others I know
about and of course many I know nothing about. If you are interested,
there are several good books on gambling which describe methods dice
mechanics can use.
What precautions can you take when playing a stranger? It is difficult.
The problem is that the clever cheater at backgammon won't cheat every
turn; only when he really needs it. This can be very effective. For
example, suppose we played a game under the following conditions: I
would have the right once in the game to call a number on one of my
dice. You would be surprised how large an advantage this gives me. Thus
you are very unlikely to spot a cheater even if you play him a long
session. Some precautions you might take are:
1) Be wary if your opponent seems to be hitting far more than his share
of critical shots, since that is when the cheater will generally use his
tools. However there is so much luck in the game that this often happens
when the game is honest.
2) Continue to play for the same stakes you agreed to, particularly if
you are losing. The best way for the cheater to win a lot of money is to
get you to raise the stakes trying to get even. If you refuse to do
this, your potential losses will be limited.
3) Be careful if your opponent is making some obviously ridiculous takes
of your doubles, particularly if he pulls them out. Of course your
opponent making bad takes is often the best way for you to win a lot, so
it is sort of a double-edged situation.
4) Be wary of large cubes. This is a way for your opponent to win a
bundle in one shot. If you aren't sure about your opponent's honesty, be
much more conservative sending that 8 cube over than you would be sending a
2 cube over. In addition, if getting paid is a potential problem this
will avoid the scenario of your winning too much and not getting paid.
Of course large cubes can be your most lucrative source of income, so you
have to just good judgment here.
It is a difficult problem. Fortunately most people are honest, but you
never know. The best advice is to be willing to follow your instincts --
if you don't like it for any reason, don't play.