Once I wrote up a deal in which South held K 5, 9 6 4, K Q J 6 2, A K Q. East opened one heart. South bid two diamonds, as who would not, but North had nothing, and South went down four, doubled.
I described South's overcall as rock-solid but mentioned that his three low hearts were a danger sign. I wrote, with a touch of irony, that to pass would have been well judged.
My column turned up on an Internet discussion group, and one of the milder comments was that if brains were rain, I'd be a desert. (Anyone is entitled to his opinion, but in the past he could inflict it on only one person at a time. With the advent of the Internet, that is no longer true.) Few people could conceive of passing with 18 points.
In today's deal East opens one diamond, and South overcalls one heart. East-West use negative doubles, so West passes and passes again when East reopens with a double. West leads his singleton diamond and the defenders operate perfectly: South loses nine tricks, minus 800.
Most Souths would overcall; I am sure I would myself. But a case exists for passing: South's diamond length is a red flag, suggesting a misfit deal.
Some experts, optimists by nature, would view South's diamond length as an asset. They would hope North's hand would be short in diamonds and would therefore produce heart support. But a decision to overcall is irrevocable: If the deal is well-fitting, North-South may be able to act later, but if South overcalls and finds a layout like today's, his fate is sealed.