Colligan, as it happens, got the idea from his wife, who pointed out that he handed out lots of free advice. Why not get paid for it? The hot line draws at least a dozen calls a day, at $2 a minute for an average of 20 minutes. “People like the anonymity,” says Colligan. He likes it, too: giving the bad news in person was no fun (nine times out of 10, it was bad). Mostly, Colligan advises against an investigation. Instead, he counsels the aggrieved spouse on how to confront the wayward other, kiss and make up. If the caller insists on finding out, he will help choose a practicing detective.

The sleuth-turned-Dr. Ruth thinks anybody’s a potential cheater. “Most men would mate with a tree,” he says. Doctors are the most frequent perps, followed by cops, “They tell their wives they’re going undercover. And they do.” Nonetheless, men call the hot line as often as women-a fact that surprises him. “Men usually have to find a cigar butt under the bed” before they get the picture, he says. But Colligan is upbeat about his desk job. “Anybody can weather an infidelity if both parties want to,” says the thrice-married gumshoe. Between calls, he’s busy writing his memoirs: “Adultery Is My Business.”