What was the name of that old song? You know—Nobody Knows the Doubles I’ve Seen.
The worst part of most of those bad penalty doubles is not only that they give away extra points on hands which happen to be lay-down. It’s that they give declarer the clue which enables him to bring home many a contract which he normally would have lost without the double.
Like here for instance:
North might have elected to bid two notrump instead of three spades on the second round, but we prefer North’s call. East’s double is inexcusable, in our book anyway. No trump trick—or even shortness in trumps to suggest partner has a good holding there —and not very much in high cards. Seemingly the club holding, over North’s club bid, was too heady a wine for East to take. South perhaps might have redoubled, but he didn’t know he was going to play the hand so well.
West opened the club seven which, surely, the double was strongly suggesting: Dummy’s ten lost to East’s queen and East then cashed his ace and followed with a small one. South had no trouble in knowing he had to trump the third round of the suit with a high spade. He ostentatiously chose the ace.
There were still two good clubs in dummy for heart discards and two trump entries. Without the double from West South’s natural play to make the hand would be to lead up to dummy’s heart king for his tenth trick. And he would expect the ace to be right after East showed up with the ace-queen of clubs.
But East’s double had the same effect as if he had shown South his hand. South knew the heart ace was over the king. So he had to find a third heart discard in addition to the two clubs. He led a low trump to dummy’s nine and led a diamond back finessing the jack in his hand. He cashed the ace of diamonds and the king of spades and then overtook his ten of spades with dummy’s jack.
The trumps fortunately broke and three of South’s four hearts went on the diamond king and two good clubs. East salvaged his heart ace but still had to, pay off on the fulfilled contract, solely he cause of his bad double.