At restaurants like Tavern on the Green in New York and Arnaud’s in New Orleans, diners sitting down for formal meals are seen complimenting the waiter on their coffee. Just a few moments later, they’re informed it wasn’t the “gourmet” brew typically served, but a cup of Folgers Instant coffee that had been “secretly switched.” The surprised patrons then heap praise on their duplicitous waitstaff.

This scene and others like it played out hundreds of times in television commercials throughout the late 1970s and early 1980s. Variations date as far back as the 1950s, and some commercials—like Chevrolet's now-infamous 2017 spot that depicted amazed onlookers marveling at the car company's numerous J.D. Power and Associates Awards—still air with regularity. Instead of using actors, the spots purport to highlight the reaction of genuine consumers to products, often with the use of hidden cameras positioned outside the unsuspecting customers' field of vision.

 

Despite skepticism, the people in these ads are often members of the general public offering their unrehearsed response to beverages, laundry detergents, and automobiles. That doesn’t mean, however, that there’s not a little bit of premeditation going on.

The idea of recording spontaneous reactions for advertising purposes dates back to the 1950s, when Procter & Gamble arranged for housewives to compare the whiteness of laundry washed in their Cheer detergent against the comparatively dingier load that resulted after a soak in the competition. The camera wasn’t “hidden” and the spokesman made no secret of his intentions—he was holding a microphone—but the women were approached in a laundromat and not a casting office. Those who appeared in such spots would receive a $108 fee, along with residuals that could add up to thousands if the commercial aired repeatedly.

This approach was refined by Bob Schwartz, a former director of the prank series Candid Camera. In 1969, Schwartz formed Eyeview Films and worked with ad agencies to capture spontaneous reactions to products. An early spot for the floor cleaner Spic and Span was a hit, and other companies and agencies followed the template. For a 1982 spot, Schwartz set up his crew in a supermarket and invited customers to try Oven Fry, a new frozen chicken product from General Mills. The most expressive reactions (“mmm-mmm!”) were invited to consent to be in the commercial.

In more controlled settings, it’s necessary for advertisers to make sure the pool of potential testimonials is suited for the product. Before filming spots like the Folgers tasting, a team of market research employees typically recruited people by inviting them to take part in polls on the street. They’re asked about coffee preferences—the better to establish whether they even like the beverage—and were then invited to a nearby restaurant for a free meal. Out of two dozen couples selected for a Folgers spot in San Francisco in 1980, two or three were selected for the commercial.

 

The Folgers spots aired for years and were memorable for how surprised people appeared to be that they had just consumed granulated crystals instead of fresh-brewed coffee. But that doesn’t mean viewers necessarily believed their reactions. A 1982 consumer survey found that consumers often found their endorsements too stiff, meaning they were prompted, or too natural, which hinted that they might be actors. Though ad agencies went to great lengths to assure authenticity, their praise made audiences dubious.

Why would non-actors shower products with compliments? It takes a bit of psychology on the part of the ad agencies. For Chevrolet's 2017 spot that was ridiculed for people overreacting to the mere sight of a car, one of the participants—who asked to remain anonymous due to a non-disclosure agreement—told The A.V. Club that the upbeat environment and surreal exposure to a new car after agreeing to take part in a market research survey left his group feeling like it would be rude to say anything negative.

“We never retook a take, but you felt really bad about saying something negative about Chevy because there were 50 cameras on you, and it was just this one [host],” he said. “He did this magic trick of making it seem like you were hurting his feelings if you said anything bad about Chevy. You didn’t want to see this guy stop smiling. It was really bizarre.”

Candid? Sure. As candid as if they were among friends and not a squad of marketing executives? That's a different story.