I think that unless the government regulates ethics, there will be very little ethics out there. If teh business world hasn’t proven this ten thusand times over, nothing will. I don’t care if it’s in print, on TV, or on a blog, I want to know when people are being paid, or are receiving free merchandise. Without knowing this, I can’t trust anything someone says.
I doubt receiving free books applies. This has been done for a century or more, and no honest reviewer hides the fact.