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If you're still bent on cheating, however, you'll get free how-to guides and handy — presumably tested — advice.

Never use credit cards, a hotel phone or let anyone take a picture.

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Toothpaste is apparently great to remove a lipstick stain. If you're still worried about telltale signs of a lover on your apparel, stop at a gas station, smear yourself with motor oil and claim you slipped while pumping gas. Better to ruin a shirt than a marriage.

Condoms are part of the philanderer's code, Mitchell says. And it's a good habit to use generic nicknames like "honey" and "dear" to avoid mix-ups when you get home.

Another part of the philanderer's creed: "I will never compromise my lover's home situation by thoughtless or selfish actions." Also: Never tell anyone what you are doing, not even your best friend.

"We don't encourage extramarital affairs. We understand them," Mitchell says.

"People who come to this site are already sitting on the fence. I help them make an informed decision, to see if the benefits outweigh the risks."

Mitchell claims he's getting 35,000 hits a day. About 70 percent of his online personals come from men, who pay about $10 a month (cheating women can post ads for free).

Mitchell admits receiving his share of angry letters from husbands and wives who've been done wrong, but says that's less than one-tenth of the e-mail he receives. "I can't say those people are wrong. Everyone has their own moral code," he says. "It's always best to be honest, and honestly, this works for me."

A philanderer isn't a bad person as much as a person who finds his marriage is missing something, and an affair might be that certain spark, he says.

"You would never know if you met me," he says. "I could be your next-door neighbor."

Buck Wolf is entertainment producer at ABCNEWS.com. "The Wolf Files" is published Tuesdays.