Mystery worshipper

Found through Tall Skinny Kiwi, The Mystery Worshipper:

Ship of Fools has an intrepid team of Mystery Worshippers travelling incognito in the British aisles and beyond, reporting on the comfort of the pews, the warmth of the welcome, the length of the sermon… The only clue that they have been there at all is the Mystery Worshipper calling card, dropped discreetly into the collection plate.

I think I’ve only attended one of the churches on the list.