Not All Exterminator Dogs Are Perfect in Sniffing Out Bedbugs

— -- It might be a bedbug’s favorite time of year. With the holiday travel season now in our rearview mirror, it's possible that bedbugs took advantage of your vacation by hitchhiking their way back to your home from your hotel or just from your Uncle Larry’s. Unfortunately, exterminators -- like the rest of us -- aren't perfect, and can sometimes fail to find an infestation. They can also tell you have a problem when you really don’t, especially if they're using dogs to sniff out bedbugs.

The bedbug-sniffing dog has become a go-to marketing tool for exterminators. And it’s no myth that, with their superior sense of smell, dogs can indeed be trained to sniff out bedbugs.

“You just want to make sure that that dog is really exposing a live bedbug,” Matt Fabry, exterminator and owner of Town & Country Pest Solutions in Rochester, New York, told ABC News’ “20/20.” “Because you can pay a lot of money for false alerts.”

Man’s best friend can steer his handler wrong, especially because often, dogs get a doggie treat each time they signal that they’re smelling bedbugs.

“And if he’s really hungry, he’s going to do false alerts ... and bark, and there won’t be a bedbug there," Fabry said.

And that’s why, Fabry also said, it’s important to make sure the exterminator shows you the bedbugs if their dog has alerted to their presence.

To see whether dogs would alert to bedbugs at a home with no evidence of bedbugs, ABC News’ “20/20” set up hidden cameras at a home in Brooklyn, New York, and made appointments with 10 teams of exterminators and their dogs.

Georgia entomologist Paul Bello, who authored “The Bed Bug Combat Manual,” and entomologist Lou Sorkin of Entsult Associates in Rye Brook, New York, first conducted a search of the home and found no evidence of bedbugs.

Still, four out of 11 dogs we met got it wrong, and alerted to bedbugs in the home even though there were none.

One exterminator’s dog -- "20/20" will call the dog “Mikey” -- smelled bedbugs on a couch, on a chair and on a bed. With each hit, the handler rewarded Mikey with a treat.

“So basically every time she scratches, she’s picking up a scent of a live bedbug in that area,” the exterminator told the homeowner.

Fabry said an exterminator shouldn't recommend professional treatment, which can run upwards of $600 per room, for a bedbug infestation unless the exterminator himself performs a visual inspection, but Mikey's handler did not do any further inspection.

Another exterminator’s dog -- which "20/20" will call “Skipper” -- then alerted to bedbugs in a different part of the house.

That company’s handler even brought in a second dog, which also alerted to bedbugs.

“After he is done, I’m going to jump in and show you the bug myself,” the exterminator said.

But after searching, the exterminator still wasn't able to find a bedbug.

“I’m not going to lie to you and say I found the bedbugs here or the eggs or anything like that,” he told the homeowner. “But 100 percent I rely on them,” the exterminator said of his dogs. “If they say there is, there is.”

He then recommended that the homeowner start treatment for bedbugs before they became “visible everywhere.”

But Fabry warns, “Make sure that they show you that bedbug, and don’t just let them tell you it’s there, and, ‘We can’t see it.’ You can see it.”

"Our industry is filled with professionals that are committed to customer satisfaction," Missy Henriksen of the National Pest Management Association told "20/20." "There is no cookie-cutter approach to pest control. It’s the handler’s job to make sure the dog is alerting to bed bugs.”

Entomologist Sorkin advises homeowners not to be pressured into doing expensive treatment when a dog alerts to the odor of bedbugs but no bugs are found. Instead, he recommends using bedbug monitors or traps that can be found in stores.

“It’s less than $100 to do some monitoring,” Sorkin said, “and thousands of dollars to do a treatment.”