mystery worshipper - definition and synonyms

  1.   From our crowdsourced Open Dictionary
    someone who anonymously visits a church service in order to gather information about how good the service was and how welcoming people were

    Leech became a "mystery worshipper", sampling a different church service each Sunday, first in Bristol and then further afield, and then reviewing it in his paper.

    Submitted by Kerry on 18/03/2016