CHICAGO (CBS)–  It’s one of the scariest things a homeowner can hear: “You’ve got mold.”

That’s just one of the scare tactics 2 Investigator Pam Zekman found one company using to trick suburban homeowners into paying for expensive mold remediation that they apparently did not need.

A company representative “was saying that everyone in this house could get sick and he was saying that I would not be able to sell this house,”  Deerfield homeowner Craig Davishoff says.

Another homeowner, Julie Newman of Northbrook, had a similar experience.

“I was scared and asked what I could do about that. And he offered on-the-spot remediation,” she says.

For an additional $800, TriState D.U.C.S  agreed to take care of Newman’s alleged mold problem.  That was on top of $400 she was already paying for duct cleaning.

“I feel like the whole thing now, in retrospect, is a scam,” Newman says.

Why?  Newman and other customers related how TriState technicians would use a swab to get material from inside the vents.  They would then put the swab into a chemically treated vial and, if it turned purple, the technicians would say the homeowner had mold.

But, the test kit instructions say on the box that the swab test “is only a screening tool that cannot and should not be used as a definitive measure of protein containing mold.”

“It could be any one of four or five biological things. And even if it were mold it doesn’t differentiate the different types,” says Larry Schwartz, owner of Safestart Environmental.”

To do that, experts certified in detecting mold, like Schwartz, send a sample to be tested in a lab. Schwartz was hired to do just that by the Parsons family after Tri-State said their Lake Zurich home had mold.

“I totally just freaked out, was envisioning the worst possible scenario,” Denise Parsons says.

But lab tests Schwartz requested were negative for all molds except one of the most common.

“That’s a usual and customary level that we all breathe all of the time,” Schwartz says.

When Schwartz told Denise Parsons that she didn’t need any mold remediation, she was visibly relieved.

“That’s wonderful. What a relief. Thank you so much,” she said.

In Davishoff’s Deerfield home, a TriState technician did a swab test in the children’s bedroom and then said the results showed “this is a real bad mold problem,” Davishoff recalled.

Then the technician pointed to white streaks on his basement ductwork as more evidence of mold

“I was shocked,”   Davishoff says.

He was shocked and concerned enough to agree to pay $1,200 more to TriState to fix the alleged mold problem.

Later Davishoff feared he’d been duped and hired Safestart Environmental to double-check for mold.

“It’s nothing more than oxidation on the metal,”  Schwartz says.

Schwartz took samples to a lab for further tests, but once again the verdict came back as “no mold.”

“I was suckered. They lied to me, then they tried to rip me off,” Davishoff says.

Davishoff wasn’t ripped off because he stopped payment on his check to TriState before they could cash it.

The operators of Tri State D.U.C.S, who have used  a variety of similar names,  did not  return calls seeking comment for this story.

Experts say if you really have a mold problem you must find the source of moisture, which is what typically causes mold. It must be repaired and any damaged surfaces should be removed and replaced.

The links listed below are to organizations that can help you select qualified duct-cleaning companies and mold detection or remediation specialists if it turns out you really need them.

The Indoor Air Quality Association

American Council for Accredited Certification

National Air duct Cleaning Association