Hi, Cindy, welcome to the forum. None of the mystery shopping companies actually hire mystery shoppers. Mystery shoppers register with the companies, which allows the mystery shoppers to apply for assignments that the mystery shopping company might post in their area. Then the mystery shoppers compete with other shoppers in the area to get those assignments. All shops are performed as independent contractors rather than as employees.
Several companies have health care projects. One that comes to mind is Second to None.