I worked for them for several years but did not do many shops for them because there were not many in my area. All was well until one incident. After that incident, I was no longer interested in shopping for them.
One project included recorded phone shops. I asked to be unassigned from one of the shops after I spoke with the target on the phone, because the call and recording quality was poor and I was not able to get all the details I needed to answer some of the questions on the report confidently.
The MSC emailed me back and said it listened to the recording and was able to complete the report. I thought that was great -- until I received payment for that round of shops and discovered that I was not paid anything for that shop.
These were targeted phone shops with a very specific script. I often had to call each target many times and document each call attempt. I did not expect full payment for the shop, but I did not think it was right that the MSC used my work and paid me nothing.
This was the only time since I started shopping 9+ years ago that I had proof that an MSC used my work without paying me. Since this MSC really did not have many shops in my area that I wished to do anyway, it was an easy decision for me to stop working for them.