[Mook]

In limit, at least, the principle of "you'll only get called when you're beat" is most often seen on the river when the flop offered one or more draws that didn't come in, and you're holding a very marginal hand.

Example, you raise from EP with [img]/images/graemlins/diamond.gif[/img]A [img]/images/graemlins/diamond.gif[/img]Q and get only the button to call. The flop comes 10-high with two clubs; you bet and are called.

Turn is a blank non-club, you bet again (usually reasonable in this spot) and get called again.

If the river is another blank, there's almost always no point in betting your unimproved AQ again. Either your opponent was drawing to a club flush and will throw his hand away when you bet (earning you nothing additional), or he caught a pair at some point and will almost certainly call, even with hands that he wouldn't have bet himself (e.g. third pair, Queen kicker). Every time you do this, you cost yourself 1 BB with no potential upside when he calls with a hand he wouldn't have bet himself.

SSHE has an entire section on this (beginning on p.193) - another point they make well is that it's most important to avoid value-betting even decent hands against tighter players on the river, since you'll almost never win when they call. Loose players, by contrast, will often call down with some atrocious holdings, so you can widen your range of river value bets (though in my example above I'd never bet the river, no matter how bad a calling station the button was).

Mook