It's not just about preserving this abstract, ivory tower concept called "journalistic integrity."
A product review is close to useless if you have no trust in its author. The crux of a review is the author's opinion about something. Whatever verifiable facts are contained in the review are still only those facts the author chooses to highlight. Consider: if authorship doesn't matter, why is a review different from a press release? In short, a review cannot speak for itself because context matters.
Let's set aside the ambiguous case of adding affiliate links and talk about out-and-out payola. If a blogger takes a secret cash payment to write a false product review, then I believe that is dishonest and wrong no matter how well written or useful the review may be. (And not to confuse what's legal with what's ethical, but taking cash for reviews on your blog might even be illegal[1].)
A product review is close to useless if you have no trust in its author. The crux of a review is the author's opinion about something. Whatever verifiable facts are contained in the review are still only those facts the author chooses to highlight. Consider: if authorship doesn't matter, why is a review different from a press release? In short, a review cannot speak for itself because context matters.
Let's set aside the ambiguous case of adding affiliate links and talk about out-and-out payola. If a blogger takes a secret cash payment to write a false product review, then I believe that is dishonest and wrong no matter how well written or useful the review may be. (And not to confuse what's legal with what's ethical, but taking cash for reviews on your blog might even be illegal[1].)
[1] http://www.cjr.org/the_kicker/ftc_votes_to_end_blogger_payol...