Case in point: a company named Gempro. Over a nine-month stretch, it made over $738K in profits -- not bad. Then one woman with an agenda came along, pummeled the business with negative reviews, and essentially killed the company...because of a misunderstanding, which the company made good on.
Go do your own research. You'll see tons of real-life stories that prove it's easier to adjust the moon's orbit than to get Google+ and Yelp to yank an illegitimate review, or reversing clearly malicious reviews. I've seen it happen first-hand with companies I know.
Until these ratings services are willing to consider these unique circumstances, I'll remain a one-star fan of them.