I first asked this question because I wondered how common it is.
I was doing a blind check at a theater when I saw a woman obviously doing an open check for another movie. I started a conversation with her. She never knew I was there to work. She told me that she had been mystery shopping for 15 years and supports herself and her daughter that way. Since she makes $25,000, which isn't much, I think her mother takes care of her daughter when she isn't in school. I wasn't sure whether she lives with her mother, but of course didn't ask.
She said that she makes $100 to $150 a weekend working theaters, and that most of her work is merchandising. She said she leaves at 6:00 AM and gets back in time to be with her daughter. She does not take any assignments in December.
This woman had a file folder with her, and as she talked she took out some paperwork. I recognized the logo, so I asked if I could see it. She let me. It was a company I work with.
Another time, I was in a grocery store that I used to mystery shop years ago, but my company had lost its contract with them. I would like to do it again, but haven't found any company that works with them. I saw a young woman with a grocery cart who had an email message in the basket. It was addressed to "Heather". I tried every way I could to see if it was a mystery shop assignment, but she was moving very fast and I didn't think it would be appropriate to follow her around. I was very tempted to say, "Hello, Heather, are you mystery shopping today?" but I didn't. She already had shown no interest in smiling or saying hello to other shoppers who passed her, as is common here, so I decided to let that mystery stay a mystery.