CHICAGO (CBS) — You see them from time to time on buses, trains, restaurants and even airplanes: Service dogs, who appear to be assisting their disabled owners.

But, a disturbing new trend is raising questions about which dogs really deserve to have special access.

CBS 2 Investigative reporter Pam Zekman took her pet collie Sophie shopping at a Dominick’s and Target store.

She was never stopped or questioned about bringing her pet into the stores because Sophie was wearing a “service dog vest” and identification badge that purchased online.

eBay alone has more than 34,000 hits for service dog items you can order– with no questions asked.

On one site, all you have to do is take a quick test. The question asked “Do you currently have a physical impairment?” Click yes and you qualify for a service dog kit, a vest and service dog ID cards.

One of the sellers promised the badge would help getting through, “airport security and even stores.”

We bought two vests, and four badges – one with a holographic seal to make it look official. Another appeared to be issued by the federal government. Two others claimed our dogs were part of a U.S registry that does not exist.

“I think it should be illegal to produce an I.D. tag like that,” said Terry Tauber, a retired police officer who helped us to undercover using fake credentials we bought online.

She used the fake badge and vest to get Ranger into a movie theater and then have a meal at a nearby diner and no one asked a single question about it.

“I was astounded about the ease of doing it, the lack of being challenged,” Tauber said.

Meanwhile, people who legitimately need a service dog are concerned that the growing abuses will make it more difficult for them to get the access they are entitled to under the American with Disability Act.

Brian Sabatino, who has muscular dystrophy, is one of them. Presley, his two-year-old Labrador can open doors, pick things up off the ground and fetch personal items, among other things.

“It’s a big help and he’s a great friend,” Sabatino said.

Pressley was trained by Canine Companions for Independence for six-months before being placed with Brian

Brian says untrained pets could pose a risk adding, “They didn’t go through the training, anything could set them off.”

Canine Companions for Independence has an online petition to urge the federal government to outlaw the sale of fake service dog credentials.

“There should be like a database, that is legit, that you can run the ID and then they know that’s a legit service dog.”

The Americans with Disabilities Act does not require people who need service dogs to carry any kind of identification card for them, and it does not allow businesses to ask too many questions. So the law that’s meant to give them access to businesses open to the public also makes it easy for the fakes to get away with it.