People are intrigued by mystery shopping. I got my current job (after passing the initial two interviews) by mostly talking about shopping in the final interview. The director and assistant director was fascinated by the whole concept. It has absolutely very little to do with analytical chemistry, but it definitely made me stand out.
Time management, self-discipline, attention to detail, ability to work under pressure, etc are all skills that good mystery shoppers have.
I think that I put, "Retail Auditor / Compliance Analyst" and then described what I did.