bftboy, on 2012-February-16, 21:09, said:
If you bid 4♠ on this, opponents shouldn't even bother looking at their hands before doubling and collecting 500 80% of the time. When your 4♠ call keeps them out of slam they will collect 800 or more and a top anyway. Maybe one time in twenty they weren't making 4♥ so it loses again. To me the real choice is between a call like 3♠ which at least gives them a guess they will sometimes get wrong, or out of the box calls like 1nt or even 2♦. I don't really expect any of these calls to work, but they might. 4 ♠ just concedes them a good result.
This kind of thinking is very wrong imo.
Sometimes when you bid 4S you have enough that you expect to make it a goodly proportion of the time : Kxxxx x Axxxx xx, for example. Sometimes you do not expect to make it, like here. But your opponents have imperfect knowledge. Sometimes when you bid 4S here your partner has extras anyway, and it will be cold. Sometimes the opponents have lots of values, but neither knows the other has extra strength.
Just because I bid 4S on this hand does not indicate that it is typical of a vul vs not 4S bid. I am attempting to exploit their expectation of what a "normal" 4S bid looks like. In this case they will not be so quick to double without trump tricks, as its rare to bid 4S vul vs not as a preempt, without some reasonable hope of making.