Everyone makes mistakes, and the saying is applicable to mystery shopping as much as anything else. Instead of insisting on perfection, accept the inevitability of error and work to mitigate the impact of your mystery shopping mistakes.
A thorough review of an assignment and all its details is the first step toward preventing a mistake, so take extra time to review guidelines before a visit.
"In order to know what you need to do, you need to review the client's guidelines and the report form you will complete after the shop visit," writes Cathy Stucker for the Mystery Shopper's Manual. "Without this preparation you won't know what questions to ask, observations to make, required purchases, etc."
Stucker also points out how many shoppers often make wrong purchases, as some assignments require shoppers to make specific purchases. Pay attention to these stipulations down to the minute details.
Also, be careful in taking notes, as nothing raises suspicion like a lone shopper with a notebook. Similarly, asking too many questions may also cause concern and blow your cover.