both you and your opponent have been drawing to a
flush or a straight. You don't make your hand, but
there's a good chance your opponent didn't make his
either. Because of earlier bets on the come, there
may be a fair amount in the pot - say, $100 in a $10-$20
games. Now let's say you are first, and you end up
with an AJ high. You think there's a 55 percent chance
your opponent made a legitimate hand, and there's
a 15 percent chance he has you beat "by mistake"
with something like an A,K or an A,Q high. In this
spot you should bet because by betting you are likely
to make your opponent throw away the A,K and A,Q high,
thus improving your chances of winning from 30 percent
to 45 percent.
In contrast, when you have a busted hand and you suspect
your opponent does, too, you may not want to bluff
if you end up making something like a small pair.
If you bet, your opponent will call with a legitimate
hand, and he will fold without one. But if you check
and then call, your opponent may bet his busted hands
as well as his legitimate ones. Thus, with your small
pair you beat his bluffs, which you could not do if
you came out betting yourself. Either way, of course,
you lose to his legitimate hands.
subset of this problem occurs in stud games where
it becomes much more difficult to remember what cards
were folded in which games. It's far more difficult
to play two games at once when stud games are involved.
This may be one of the reasons why stud, a popular
game in many B&M cardrooms, occupies a far smaller
percentage of online tables. There has to be some
explanation because by playing online you have one
huge advantage in stud that you can't employ in a
B&M cardroom: You can literally write down all
exposed/folded cards and never have to guess how many
diamonds were folded or whether there are two sevens
left, or three.