I responded to a message from GfK about completing one of their audits on a tight time frame. I asked for a substantial bonus, and it was accepted immediately.
As I was completing the shop, I got an e-mail stating the shop was cancelled. After responding and stating I already had the shop done, and asking why it was cancelled, they were very up front, saying "We were told to find another shopper in case the original shopper didn't follow through on a trip back that was needed."
Moments later I got another message stating they would still pay me the shop plus bonus as long as I entered my data as I had originally stated.