Flowers and chocolate aren't the only big sellers for Valentine's Day. There's also spyware. The use of tracking devices and hiring of private investigators surge around this holiday — an opportune time to catch a cheating spouse. CUPID ON THE CHEAP: Valentine's shoppers expected to spend less SURVEY: Couples say they'll cut back on gifts, not sex BETTER LIFE: Help with your Valentine's Day plans "If there's anything going on, a spouse will more than likely make contact with a lover on Valentine's Day, the day before or the day after," says Ruth Houston, author of the book, Is He Cheating on You? 829 Telltale Signs. Private investigators agree. "Valentine's Day is a day of lovers, and sometimes the lover is not a spouse," says Jimmie Mesis, editor of PI magazine. That's why, he says, investigators are often busy this time of year. Mesis says suspicious spouses are also turning to spyware, which costs less than a detective. "They do their own CSI work," he says. His website's sales of GPS trackers are more than 20% higher in the three weeks before Valentine's Day than at other times of the year. Sales of spyware to track spouses — his customer service representatives talk with buyers about how they'll use the items — were 141% higher in the past four weeks than the monthly average for the preceding six months, says Todd Morris, CEO of BrickHouse Security. Such devices, retailing for $50 to $400, include cameras hidden in alarm clocks, light scanners to detect evidence of sexual activity and devices to monitor e-mail. Morris says he expected more people to stay home with their spouses in a weak economy, but sales suggest otherwise. "Apparently," he says, "money troubles don't stop the philandering." The dismal economy is making it more difficult, though, for people to afford a private investigator. David Hill, an investigator in Tuscaloosa, Ala., says he has had lots of inquiries in recent weeks, but often callers cannot afford his $1,500 retainer. This Valentine's Day is one of the few in the past two decades that has not triggered a surge in clients, says Kelly Riddle, owner of Kelmar & Associates in San Antonio, a firm of 39 private investigators. It's the economy, Riddle says: "If they have a cheating spouse with a job, now is not the time to rock the boat." How often spouses are unfaithful is unclear, because studies report varying results. In a 2006 survey of 3,000 adults by the National Opinion Research Center at the University of Chicago, 22% of men and 13% of women admitted to infidelity. The heartbreak is tough to watch, especially after a spouse sees proof of the infidelity on video, Riddle says. He recalls a Valentine's Day case of a man who had lunch with his wife and dinner with his lover of nine years, with whom he had a child. The man basically had two wives, Riddle says. "He brought a dozen roses to each of them." Guidelines: You share in the USA TODAY community, so please keep your comments smart and civil. Don't attack other readers personally, and keep your language decent. Use the "Report Abuse" button to make a difference. You share in the USA TODAY community, so please keep your comments smart and civil. Don't attack other readers personally, and keep your language decent. Use the "Report Abuse" button to make a difference. Read more