I was a mystery shopper at churches a few years back. I got paid to attend different churches, evaluate the congregation, the quality of the service, the building, etc. If you have the time and inclination, here is the article I wrote about it a year or so ago: https://jegelkrout.medium.com/i-was-a-secret-shopper-at-churches-b93e89175773?sk=dbee8c35899718dd095af178ff4b12d2