You've probably seen the ads in the newspaper or in your mailbox: a huge, frightening-looking dust mite accompanied by warnings that your health could suffer from dirty, moldy air ducts. But have no fear: for a low price, like $49.95, you can have them cleaned — you might even get a 10 percent discount if you're a senior citizen.According to the Better Business Bureau, it's a scam called a "bait and switch," and the BBB says it's happening all across the country. In fact, the BBB claims that dozens of connected companies are involved in the airduct cleaning scam, systematically ripping off homeowners for more than a decade to the tune of millions of dollars.Over the years, hundreds of homeowners have logged complaints with the BBB, all sounding similar: Once inside a customer's home, technicians routinely mislead them into paying hundreds or thousands of dollars for additional work. Many were told they had dangerous mold. Others had their homes unnecessarily flooded with noxious chemicals.

Some said they were afraid of the workmen. All said they were duped into paying hundreds more than the promised $49.99 advertised price.It sounded like a story for the Hansen Files, a new franchise from NBC's Dateline, so we began our own investigation.We found senior citizen volunteers who allowed us to wire their homes with hidden cameras to see what would happen when we responded to one of the ads. Even we were stunned by what we saw. Not only did our cameras catch the technicians scamming nearly $500 from our volunteer, they actually left the house in worse condition than before they arrived.A few weeks later, we asked our volunteer to make another appointment, this time to have her furnace cleaned. And this time, Chris Hansen was there to let the technicians know our cameras had recorded their scam, and to see what they had to say.Early on, we learned reporting this story wouldn't be easy. We began by digging into one company, and then another, and then the histories of some of the people behind them.

We found many of the businesses opened up shop only to disappear within a matter of months, but would then appear again under a different name. Sometimes, it was even hard to determine exactly who owned many of them. The paper trail left behind was limited and sometimes inaccurate. One business was registered using the name of the real owner's dead stepbrother. Another was registered in the name of an owner's bodyguard. Several to convicted felons, one a killer.But our reporting led us to one revealing fact: dozens of the rogue businesses all across the country were run by a rotating list of the same individuals who kept popping up over and over again.As we began to connect the dots, we saw that some attorneys general and judges have ordered these companies to be shut down, forbidden their owners from doing business in their states, and ordered them to pay hundreds of thousands of dollars in damages. But most of the time, the scammers simply took off to set up shop in another state.Bottom line: If you think you need your air ducts cleaned, check with both the Better Business Bureau and the National Air Duct Cleaners Association before answering the cheap ad in the newspaper.

Watch this Web-exclusive video of Chris Hansen confronting air duct cleaners: And here's a closer look at the dirty business of air duct cleaning scams, and how you can avoid them, with Michele Mason of the Better Business Bureau:To watch the full story on air ducts, follow this link. oransi vs alen air purifierAnd here's the full episode of Hansen Files, with additional looks at psychics and the questionable backgrounds of professionals.sanuvox portable air purifierYou can see more on the Dateline home page.bionaire germ fighting air purifierDo you have ideas for an investigation? Share your story ideas with Open Channel Send us a document Follow Open Channel on Facebook Keep up with Open Channel on Twitter

Sign up for e-mail alertsThe National Air Duct Cleaners Association (NADCA) participated in an undercover investigation by Chris Hansen and Dateline NBC to expose companies that use bait and switch tactics to take advantage of consumers. The investigation culminated in a segment that aired January 30, 2011, featuring NADCA President Buck Sheppard as the industry expert. After witnessing one of the scam operators in action, Sheppard was taken aback. “It was amazing how unscrupulous some people can actually be,” he noted. The segment focused in part on a representative from a company called Duct Masters, out of Hebron, Kentucky. The consumer called the company expecting the advertised price of $49.95, but instead ended up paying almost $500. Even after paying the higher price, the job was not done properly. Dust and chemicals were released into the living space of the home and the system was still filthy after the Duct Master representatives were finished. Reflecting on the segment that aired Sunday night, Sheppard added, “I believe the Dateline piece was well produced and highlights the need for better oversight by the individual states.

For those so-called ‘duct cleaners’ who have no standards by which to measure their work, they should be aware that NADCA and its combined membership are always pushing to better educate our consumers. Through better education, consumers aren’t as likely to fall prey to these types of unscrupulous and shady practitioners, since they know how to choose a professional duct cleaning company. And that’s no BS.” AAA Heating & Cooling has been a member of NADCA Since July 2000.Homeowners need to know! Beware of the duct cleaning ads from companies who say they’ll clean all the air ducts in your house for between $49 and $149. These “blow-and-go” firms are using “bait-and-switch” tactics. They’ll scare you, then snare you. Once in your house, you can count on hearing that you need more and the price will go up. Usually they send one person, not in a uniform with no more than a shop vacuum. We suggest you get the answers to the following four questions before you let them in your home.