When I read the OP, I envision shoppers cutting corners and falsifying reports, schedulers misleading shoppers as to the amount of work and/or pay for a shop, and editors changing answers to make sure a client does not reject/challenge a report.
I have written some very good and some VERY bad evaluations. I've only had a client ask about two of them (both bad). I explained what happened to the project manager and, in once case, provided an audio recording to back myself up. In the other, the client reviewed video surveillance. Both shops went through and I was paid. I continue to work in good standing with both MSC's. I've not been around or done as many shops as some folks. However, I have completed quite a few shops over the last three-plus years to feel very comfortable in stating that MOST MSC's work professionally with shopper reports.
Do schedulers make shops sound more attractive than the really are? Yes. I'll roll my eyes at quite a few of the email ads I see. However, as long as they pay me what they promise and honestly answer questions when I ask about workload, I'm good. I've only had two schedulers mislead me about the amount of work in a shop. One replied with an "LOL" when I asked about the expected workload after my shop was approved. I am hesitant to do more shops for that MSC (though they seem to be a popular one for many folks) - I figure it is a scheduler issue. The other MSC is notorious here...
As for shoppers.... There have been quite a few things shoppes have admitted to, when posting here.... Editors and schedulers have posted about some antics some shoppers have tried to pull, too. I am certain that there are a handful of shoppers who cut some corners. I also suspect that most of them don't last long.... I don't have the background to know if this is a new issue or one that's been around for as long as there have been mystery shoppers. I suspect, so some degree, it has been around for quite a while...
Hard work builds character and homework is good for your soul.