Writing Product Reviews of Stuff You Don't Own
Don't forget that you can always leverage OTHER reviews to write your own reviews! You can read them, then report back on what the general consensus.
"[Product Name] has over 400 reviews on Amazon and received a rating of about 4.5 stars. That's an amazing feat for ANY product!"
"More than one forum had a few complaints from folks saying that customer support was a common issue with [Product Name]"
You can also take screenshots of specific parts of reviews. DO NOT copy/paste content onto your own blog, or screenshot large portions of someone else's review! It's not helpful, and might be copyright infringement. What you can do is screenshot a portion of the review that you find interesting and add commentary on it.
Pro Tip: The above screenshot is a tiny portion of a 1200 word review, and the highlight was added by ME. By taking a small piece of something, changing it, and adding commentary, you make it your own. In addition to this, I would have to write a review that was completely original, and not just a "spun" copy of this other guy's review.
That is the difference between copying someone's content to try to drive traffic to your site, and leveraging other reviews to enhance your own.
NOTE: Amazon doesn't allow this, and doing screenshots of reviews on Amazon will get your account banned if they find you doing this. Just summarize what you read on Amazon reviews if you find anything worth mentioning.