Help
To clarify my point, I made up two hands(with random hand generator under some restriction),
On both hands South opens 1♠ and West overcalls 2♣, some of you may not agree the overcall on first hand(I think that is acceptable) but few of you have not seen people overcall with something worse than that.
As you can see the best result for NS on both hand is to defend 2CX, but if such a hand occurs in any event, very few pair are going to achieve this result.
On the first hand a lot of North may not trap but compete with negative double and end up in playing some partial. On the second hand even North makes a trap pass most South reopen with 2♠.
That is, by playing negative double, we do give up some chance punishing opponent.
How about trap pass/reopen with double more frequently? Let's restrict the discussion to the following sequence.
1 level open-(simple overcall)-pass-(pass)-?
Partner either has a weak hand or a trap hand. Therefore I double whenever
(a)I have doubleton or less in opp's suit
(b)Want to defense when partner is trapping
©Can accept the potential damage if I reopen with non-standard takeout shape, either I can escape later or it won't be that bad if partner bid my short suit.
For example, if the bidding goes 1♠-(2♣)-P-(P)-?, with South's hand in first example, I double and if partner bid 2♥ I accept it. With South's hand in second example, I double in case partner is trapping and bid 2♠ over partner's 2♦/2♥, not announcing I have extra, but saying I only offer two choice, playing 2♠(if you're not setting trap), or defensing 2♣X(if you're setting trap).
With this agreement we can reopen with X more often without risk. As responder, we feel more comfortable to trap with 4 mediocre trumps in opp's suit) without risking too much even though 2NT/3NT or negative double(when most strength is in opp's suit!) is an alternative, because partner almost always reopen with X.
This approach may have further advantage, that is, your partner is easier to judge when you reopen with something else. Back to "another trap pass problem", if partner would have reopend with X on "defensive 5521 hand"(For example ♠AJxxx ♥KQxxx ♦Qx ♣x, intend to bid 2♥ over 2♦ response), then 2♥ reopen must be highly offensive, with ♠K8 ♥J6 ♦A873 ♣K9863 this hand could be closed to 4♠!
Thanks if you're willing to read such a long post, and feel free to comment or to share opinion.