Shoppers Critique used to have one chain here in the Chicago area but they haven't had many in a couple of years...last I heard they were only doing shops on those that just opened recently. They now have haircut shops that are a bit more upscale (and there are only two of these salons in the Chicago area).
Secret Shopper does another chain of hair salons in the area but I only see those once every few months.
I, too, am curious to see if any other MSCs have haircut shops....
Silver certified (since 2009) and willing to do shops all around the greater Chicago, NW Indiana, and Southern Wisconsin areas (including airports!.