ibes007,
If that is your concern, you are better off with errors and omissions insurance or a personal liability insurance policy.
No, I have never heard of anyone being sued for performing a mystery shop according to the MSC guidelines. I have monitored this forum and the volition forums and attended IMSC conferences for many years and have never met or heard from anyone who has heard of such a thing actually happening.
If you are concerned about shops that might land you in court as a witness, then you might want to avoid revenue protection shops aka integrity shops, and shops that require you to report on whether IDs were checked for liquor and/or tobacco sales.
In addition, if you do recorded shops, be sure that you are up to date on audio recording laws because 13 or 14 states have criminal penalties for audio recording without prior permissiin of the other party. For details, please see the second thread in the New Mystery Shoppers area of the forums. An LLC will not shield you from criminal prosecution, btw.
Based in MD, near DC
Shopping from the Carolinas to New York
Have video cam; will travel
Poor customer service? Don't get mad; get video.