It's a laboratory on wheels: HealthFair calls itself a national leader in mobile testing for cardiovascular disease, cancer and other common diseases.
The company's fully equipped buses are stocked with ultrasound equipment and diagnostic devices.
The company advertises a series of six tests, including an echocardiogram, an EKG and a stroke-carotid exam, all for $179.
HealthFair says these tests would normally cost about $2,300 and the company says aside from a 92-percent savings, the tests offer consumers invaluable information.
"A significant proportion, percentage, of people out there that have sub-clinical diseases, that are unaware of it, that they're not seeing their physicians on a regular basis, they're not getting treated for hypertension, their cholesterol values," said Dr. Robert Oristaglio, chief medical officer for HealthFair.
Oristaglio says these tests can help detect early warning signs of diabetes and heart disease.
But many physicians, like Dr. Daniel Eisenberg, the director of cardiology at Providence Saint Joseph Medical Center in Burbank, say in most cases, consumers should avoid these types of tests unless ordered by a doctor.
"With these, it's a company that comes with a truck to a neighborhood, or has a clinic that you just go to that doesn't really have doctors or nurses, just does these tests, and it's really not done in the standard that you'd want, so I would say stay away from these companies," said Eisenberg.
Eisenberg says one of the tests routinely given to patients as part of a diagnostic package is the peripheral arterial disease test.
"If you are just a normal person who doesn't have diabetes, then you wouldn't necessarily get this test and it wouldn't save your life unless you had a very high-grade blockage," said Eisenberg.
"The evidence shows that it does not provide any benefit to get that test," said Dr. Virginia Moyer.
Moyer chairs the U.S. Preventive Services Task Force, a national panel of healthcare experts that has issued recommendations on the merits of health-screening tests.
The task force issues letter grades from "A" to "D" based on whether these tests provide more benefit than harm.
While screening for high blood pressure in adults has an "A" recommendation, testing for coronary heart disease in adults with low risk for heart disease is given a "D" grade, and is not recommended for most people.
"I hate to see resources wasted on tests that aren't going to help somebody when so many people are not getting the tests they need that are going to help them," said Moyer.
But HealthFair's top doctor says the screenings provide an important tool that could diagnose undetected health problems and potentially save lives.
"We need to know that information from a primary prevention perspective so that we can get these people early, get them into seeing their physicians, treatment programs and then see if we can impact," said Oristaglio.
Another company, Heart Check America, offered its clients comprehensive diagnostic tests, including virtual colonoscopies and lung and heart scans, at a much higher cost.
To consumers like Constantino Gabriel of Monterey Park, it sounded like a great idea.
"Other family members have either had cancer or heart problems and I just wanted to check and take a look and see if this was something that I may need further medical attention in my health," said Gabriel.
But after recently spending more than $3,000 for a 10-year package of scans for himself and his wife, Gabriel discovered the company had gone out of business.
Eyewitness News went to one of Heart Check America's two local offices to find out what happened.
At the Heart Check America office space on Wilshire Boulevard in the Brentwood area of Los Angeles, there's nothing inside.
A few months ago, without warning, Heart Check America shut down its Wilshire Boulevard location, along with offices in Irvine and several other cities across the nation.
Eyewitness News attempted to reach Heart Check America multiple times for a comment. The company's phones lines have all been disconnected and no one responded to emails.
Customers like Contantino Gabriel, who are out thousands of dollars, are holding out little hope they'll get their money back.
"It wasn't a body scan, it was actually a money scam," said Gabriel.
Consumers should be cautious before pre-paying for health screenings, especially if the tests are spread out over several years.
If you do go for mobile health screenings or other diagnostic tests, make sure you follow up with your own physician to go over those results.
Again, many doctors and health care experts say most people shouldn't be wasting their money on these tests.
Before signing up for a health-screening test, you should first check out the recommendations by the U.S. Preventive Services Task Force to see if the test is right for you.