Read the "Nuts and Bolts . . ." thread in the New Mystery Shopper section for how this works (that section is on the index page of the forum). Whether it is worth doing or not is personal taste and tolerance. You won't make big bucks, you won't come home from the mall with bags of freebies to evaluate. It is work, it takes time and patience as well as reliability. Like any self employment it offers tax advantages and moderate schedule flexibility.