OK, I have to step in here as there are a lot of cynical misconceptions stated. I once sold audio gear, non-commissioned, but always looked to build repeat business. I was the #2 salesperson in the shop (behind the manager) because I knew what I was talking about and could help the customer find a system that fit his/her needs and budget.
For the past 30 years, I've been a reviewer, for whom, I won't say. I can't speak for all reviewers but I work to specific standards. Have I received freebies? Yes - a few, but mostly minor things such as low-to-mid--range phono cartridges. Do I get to keep the review gear forever? No - I work on a roughly two-month schedule and the gear always goes back. Do the manufacturers/distributors pay me for the reviews? No - I'm paid by the publication only. Must they advertise? No - Selection of the gear to review is strictly up to me. Do I take advantage of "accommodation pricing"? Yes - but not all my system gear was acquired that way. There's a fair amount I bought retail or used. Do I play favorites? No - If I get a piece in for review that just doesn't cut it, you never see the review. I won't waste my time or yours with a bad review. I stick to gear worth reviewing.
Any questions/comment?