Raising to Muff or Semi-Bluff

Raising as a pure bluff with a hand that has no chance of winning if called is a tricky play, too risky to be attempted often. It is usually done only when there are no more cards to come, often when you didn't make the hand you were hoping to make but are trying to convince your opponent you did, Presumably your opponent has a decent hand to bet into you and is reluctant to throw it away when you raise. In limit poker, raising as a pure bluff can succeed often enough to be profitable only against a very tough player who is capable of making super-tough folds. The weaker the player, the more likely he is to call your raise with any kind of hand.
Pure bluff raises are a more important part of no-limit poker. Indeed some world-class no-limit players, like 1982 poker champion Jack Straus, are famous for their ability to bluff raise successfully. However, the fact that bluff raises are more important in no-limit than in limit doesn't make them any less difficult or tricky to use; it only makes them more costly when they are misused. (See Chapters Eighteen and Nineteen for a further discussion of bluff raises and bluffing in general.)
The semi-bluff raise is a more significant and frequently used part of a good poker player's arsenal. As with the pure bluff, you make a semi-bluff raise in the hope of winning the pot right there, but in contrast to the pure bluff, you always semi-bluff with more cards to come and with a hand that can improve, so there is a reasonable chance you will outdraw your opponent and win the pot even when you are called.
As we observed in the last chapter, the semi-bluff raise can also be a good defense against someone else who may be semi-bluffing. When you raise a possible semi-bluffer, that player usually has to throw away a semi-bluff hand. When he calls your raise, you can be pretty sure he has what he's representing. So an added benefit to your semi-bluff raise is that you have gained a bit of information. Furthermore, your opponent may fear you have the best hand, and check to you on the next round, giving you the chance to take a free card.
Thus, even though you may not achieve your primary goal when you raise - in this instance, making your opponent fold a semi-bluff hand - you often achieve secondary goals - such as gaining information and getting a free card. Similarly, when you raise to drive worse hands out but one of your opponents calls {and is getting proper odds for the call), you have at least achieved the secondary goal of getting more money in a pot you think you are the favorite to win.