“They didn’t feel like a team,” she said, “and that made me doubt the quality of my care.”

Mr. Peterson said the secret shopper’s presentation of these and other analyses had his leadership team “spellbound.” A plan to make Stormont Vail Health a better place to heal quickly followed.

For example, the medical center created new tenets of employee behavior designed to improve the patient experience. Staff members were encouraged to greet people in the hallways rather than thumbing their phones while walking.

“Keep your eyes up. Socialize with patients instead of talking about patients. Tune into the social determinants of health. Everyone has a story,” Mr. Peterson said.

Secret shoppers have illuminated many aspects of the patient experience. In a 2016 study, secret shoppers contacted 743 primary care practices across California. Over 70 percent were unable to make an appointment with the original clinician they contacted, illustrating how challenging it can be to access health care. Secret shoppers have cut telephone wait times for patients of orthopedics clinics, and this spring a secret shopper study showed that more than a third of patients seeking treatment for opioid addiction were denied an appointment.

The experiences of vulnerable patients like these can be highlighted by secret shoppers. A second secret shopper from Etch Strategies presented to an emergency room in rural New York wearing sweatpants and a T-shirt with the name of an indie band. She had not showered for three days and told the desk clerk she didn’t have health insurance. This secret shopper, who in real life works in marketing and qualitative research, said it made her nervous to pretend to be someone else. But the disguise helped her make an important discovery.

“From the second I walked in, people were very short with me,” she said. “There was no eye contact. People didn’t even introduce themselves!”

At one point, a phlebotomist got the secret shopper’s blood “all over my arm and a sheet.” There was no apology. No explanation. The secret shopper said there was a stark difference between this treatment and the care she has received when fully insured and professionally attired.