You will never be able to account for that. The beauty of the way this proposed system would work is that you will be able to look at the rating that commenters give in conjunction with the reviews. I as a consumer am not inclined to give much thought to people who say “great” with 5 stars or “sucks” with 1 star. I look for detailed reviews to go along with ratings, as that gives you a better idea of how other consumers perceive the product. Although they could get around this by implementing a minimum character count.
We aren’t advocating mandatory reviews, but tying ratings to reviews. Meaning in order to give a rating, you must write an accompanying review.