Based on my listing in a NACE database, a company sought out my opinion on their product. From memory, it appears identical to the one mentioned above (although I don't recall the brand-name at the time).
The company provided a packet of info for review, and a "promise" of a payment when I provided my review, with the possibility of a second review and payment.
The packette of info actually stated they didn't want my opinion on how well the system worked, because they had lab test data and a patent.
Well, I was honest, and gave them my honest opinion on the technology and application of their claimed technology.
No suprise, I never heard from them again.
...I'm sure some engineers provided a really great sounding review...