A cop walks into a donut shop.
Far from a fat-cop joke, that sentence could be the beginning of the end for a Dunkin' Donuts shop owner who tried to swap out DD-brand munchkins for a cheaper alternative.
"I used to be able to reach in and pull out a donut, and be able to smell and determine whether it was a Dunkin' Donut," Michael Mershimer, former head of loss prevention for Dunkin' Donuts and Quiznos, told ABCNews.com.
Dunkin' Donuts didn't just rely on Mershimer's nose. It has a lab in Canton, Mass., where Dunkin' investigates fraudulent pastries with the zeal of a forensics team. Donuts are weighed, measured, taken apart by experts in white lab coats. They are tasted, sniffed and mashed to see how they crumble.
Across America's thousands of franchise restaurants are more than 300,000 undercover food cops, pulling apart donuts, inspecting sub sandwiches, and checking burger patties for authenticity. The mystery shoppers are part of a loss prevention strategy that tries to ensure major brands - Quiznos, Baskin Robbins, Burger King - maintain consistency and don't lose money to crafty franchise owners.
Parent corporations are ever vigilant to protect their brands as well as their share of the dough. Mershimer once staked out a donut shop in Michigan through several nights, following its trucks to see where the genuine Dunkin' donuts were being delivered, to find the local franchisee was selling them to hotels and gas stations, and keeping the profits.
Dan Ribacoff is a private investigator who has staked out thousands of franchises for quality assurance, using tactics that ranged from a surveillance van equipped with night vision goggles for a steak house to Dumpster diving for a Rita's Ice shop.
"After they closed, we'd go in and jump into the Dumpsters and find non-Rita's syrup," Ribacoff said.
While working for Baskin Robbins ice cream, Mershimer "busted" a franchisee who bought tubs of cheaper ice cream and used a hot iron around the sides and bottom to make it easy to pour into Baskin Robbins tubs.
Sandwich companies like Quiznos are equally determined to protect its image, covertly buying sandwiches for inspection.
"We'll tear the whole sandwich apart. How much did the cheese weigh? How much did the meat weigh?" Mershimer said.
"It's all about controlling loss and making sure that franchisees are following brand standards. That's why you have Big Macs everywhere with no ketchup. It always has to have the special sauce," Mershimer said.