If you search the KDP author boards, or any number of indie artist discussion boards, you will quickly find the topic of reviews being discussed. Some indie artists tend to place a lot of importance in receiving reviews for their work while others simply dismiss them. At one time I will admit that I was in the former camp, but recently I have moved over to the "don't worry about them" camp.
One must remember that reviews are opinions, and opinions are highly subjective and subject to one's mood, expectations and, in a lot of cases, a person's reason for leaving the review in the first place. This holds true for both good and bad reviews and it doesn't take a lot of time to find reviews for almost anything that can be considered highly suspect.
These false reviews are very easy to find; one only needs to type "review of XXX" in an online search engine and you will quickly find reviews for almost anything, and within those reviews you will find both positive and negative reviews. As you peruse the reviews, it will quickly become apparent which reviews have a hidden agenda.
Some businesses have been fighting back against false and unfair reviews and have even sued the reviewer for damages in addition to a retraction of the original review. This may work for a large corporation or even a local business that can prove that they have been damaged by such a review, but for indie artists, this generally is not a viable option.
The best advice that I have seen from other indie artists is to simply ignore the false reviews and trust that consumers are smart enough to be able to spot a fake review. Also remember that reviews are not normally the deciding factor for a purchase and someone considering a purchase of your book, song or other creation will most likely not base their final decision on a few obviously skewed reviews (either good or bad).
Finally, for those people who leave reviews as an attempt to get a person or business to purchase their service, forget it. We may be indie's but that doesn't mean that we are naive. Fake reviews are about as effective as spam emails in getting one of us to purchase your "much needed" service to further our success as indie artists.