I think all of us have fallen prey to this one. It's fine in the beginning. But the MSC keeps changing the rules and the payment, sometimes without telling anyone. They seem to randomly change the parameters sometimes with only minutes to spare. We signed up for some of the C-store checks, but there are so few items with actual prices on them, there is nothing to report. The first time we did them they paid us anyway for doing the job, even though we didn't get many prices. The second time they sent us to the same store they said we didn't get enough prices, and we could go back and do it again, or they wouldn't pay us. We told them to pound sand. My son and I tag teamed the stores, one of us would go inside, and get the prices, the other would do the input in the shop outside. And we would switch off a couple times while we were at a store.
That wasn't so bad though, it was the grocery stores that broke us. The first time we drove 2 hours to the store, we spent 2 days at the store, so that's 4 hours driving, x 2. Eight hours in the store, changing out phones and chargers several times so that we could keep working. We even bought our lunches from the deli in the store. Same story with the MSC, the prices we found were enough the first time, the second time though they wanted something different and refused to pay us.
We decided that the price check shops aren't worth our time or effort.