I am part of an app development team called 5ivedom in the Nook store and we have found that there are many times when the reviews on our apps (particularly the negative ones) are written by other developers who are not playing ethically and choose to post fake reviews. From that, I have developed a somewhat jaded point of view of negative reviews of any product - because I believe they are either written by the minority who might have had a negative issue, by the uninformed who don't take the time and effort to understand how to work an app, or by those who feel it is better to knock down a good product than to work harder to create better products on their own.
Similarly - I quit even looking at the Free Android App of the Day in the Amazon store because I could not believe the number of reviews from people slamming the product because it was not what they wanted. It was free people! Either be gracious and enjoy it or delete it if it does not meet your needs.
In my opinion, it is the average score that is the best indicator of the quality of a product.