This topic appeared in 2010: [
www.mysteryshopforum.com].
The did a slew of shops for Confero that were short and easy. I got 10s for the first few then 8s. I asked the reviewer what happened. She said that they reserve 10s for more difficult shops. I don't know why she originally gave me 10s. I did all of the shops the same, several locations every time they came up. Confero usually solicited me. (They were hard to fill? I did them well?)
The problem with giving higher scores to more difficult shops, which I understand on one level, is that it weighs heavily on a shopper's score when she has two dozen easy shops scored 8. It's nearly impossible to increase one's average unless one does a lot of shops for that MSC, which I didn't, except for those particular ones.
The same reviewer would occasionally give me a 9 or 10. I don't know why. Maybe she felt guilty giving 8s to reports that probably required no editing.