Even if you can`t bet for value and it doesn`t make sense to bluff, it could still be good to bet. This situation occurs when

a) you probably have the best hand
b) your hand is not strong enough to bet for value
c) your opponent won`t put more money in the pot on later streets unless he improves to a hand that beat you

Example:

You raise preflop with 88 and get called by a somewhat tight but not very aggressive opponent. The flop comes K92 rainbow. If you bet you think you will only get called by a 9 or better so you can`t bet for value. You can`t bluff either, since he won`t fold any better hands. You should probably still bet though, because you want to make your opponent fold worse hands that will only put more money in the pot if it improves to a hand that beats you.

Let`s say your opponent hold a hand like AQ. You have the best hand on the flop, but your opponent has 6 outs to improve to a hand that beats you, i.e. by the river your opponent will win the hand 1 in 4 times, which gives him about 25% equity in the pot. So if the pot is $10, '$2.5 belongs to him'. If you bet, he will fold his hand and you will 'steal' his $2.5 equity.

People often confuse capitalizing on dead equity with protecting your hand. By betting your hand, you protect it, but thats more a consequence of the bet than a reason to bet. The real reason is that you want to make your opponent give up his equity.


Visit:
Reasons to bet I: Valuebetting
Reasons to bet II: Bluffing