I don't do a lot of product reviews, but once in a while I do. When I do, it's because I found something I liked and want to spread the word, not because I was paid to write about it.
I review the books I read on a regular basis, and saw a disclaimer on another blog where the blogger stated that there was some regulation that says that as a blogger you are required to state whether you receive compensation for any reviews.
If that is in fact true, let me state for the record that I have not been compensated in any way for any of my posts. The opinions are solely my own. I have not received any free products to write about. Anything I acquired for the purposes of reviewing were either purchased by me or in the case of many of the books borrowed from the library due to my interest in them.