"When I saw it the first time, it shocked me," one former employee told CBS News chief investigative correspondent Armen Keteyian.
The former employee, who asked for anonymity, says inside the clinic, prescriptions for dangerous addictive drugs like the painkiller Vicodin, the muscle-relaxer Soma and the anxiety drug Xanax are illegally handed out like candy.
"In reality, its drug dealing," the former employee said.
Law enforcement sources estimate there may be tens of thousands of these so-called pill mills operating nationwide.
To see for ourselves, we sent a healthy woman inside the clinic, posing as a new patient in pain.
The receptionist says, "Do you have your medical records? MRI records?"
"No," the patient says.
"Can I see your ID please?" the receptionist says.
It turns out she didn't need any records just cash.
"Our office visits are $80," the receptionist says.
Once paid, an attendant checks weight and blood pressure. Then it's time to meet the doctor.
"What's your name?" the patient asks.
"Manuel Hernandez," is the reply.
"You are the doctor here?" the patient asks.
"Yes, with my boss," Hernandez says.
In violation of Texas law, there's no physical exam, no review of medical history, and watch how easily we get our drugs of choice.
"Can I get Vicodin or Lorcet?" the patient asks.
"You said Lorcet and Soma," Hernandez replies. "You want that?"
Is this the kind of stuff the Drug Enforcement Administration would like to put an end to?
"Absolutely, absolutely," Joe Rannazzisi, a top DEA official, told Keteyian. "What they're doing is way outside the scope of medical practice."
And increasingly, it appears outside the reach of the DEA, despite a recent rash of arrests. Only 249 doctors have been arrested by the agency in the last four years.
"These guys are very very good at staying under the radar," says Dr. Andrea Trescot, a leading pain specialist.
"What they're causing are patients to get addicted and potentially die," Trescot says.
(***OR*** "It is a huge societal problem cause society has to pay for the addictions and the deaths that occur because of this.")
In all, CBS News sent four people into the Houston clinic. Same scenario: no exam, no records, same result.
Our prescriptions were all faxed to this nearby pharmacy, where we got hundreds of Vicodin, Xanax, Soma 720 pills total each and every one prescribed by one man. Keteyian caught up with him in the parking lot at the end of another very busy day.
He asks: "Why are you prescribing painkillers to people who go in there?"
"Ask my boss," Hernandez says.
"No, you're the guy who's doing it. Why are you prescribing painkillers without physical examination and without looking at anybody's records? Why is that? Are you even a doctor, Dr. Hernandez?" Keteyian asks.
Fact is, Manuel Hernandez is not a licensed doctor. So how'd we get all our pills? Against federal law, the clinic put them under the name of a doctor we never met and couldn't find.
State records show the clinic was set up by still another doctor, Rodolfo Giraldi, who failed to respond to numerous requests for comment. But right after our first letter, the door was locked his clinic closed, for good.
But there's nothing to keep him from opening at another location, and going right back into the drug business.