A few weeks ago I sent my resume to a Mystery Guest company. Not for a new job, but just as something fun on the side (you get paid a few bucks in transportation costs, that's it). I got a call back and they wanted to test me by doing a mystery visit at a local temp office. I visited, wrote my report and mailed it. Today I got the message that they were 'very pleased' with my report and will be sending me a contract so I can be added to their database of capable mystery guests.
Fun! Now hopefully they're gonna send me to restaurants as well and not just shops and service-providing offices. :)