My best friend has the same kind of business I do. He lives in the Seattle area. He got a Yelp negative review. He did everything to pacify this customer, all to no avail. Eventually the customer admitted the problem was not even caused by his business, but would not change her Yelp review.
Which brings me to this: Sometimes I go in a business and I'm awed by what they do. Case in point is Buffalo Wild Wings in Brea. It's a new business and they have both indoor and outdoor service. In fact, for you smokers they even have a designated smoking area. It's a two story building with over 120 TVs. It's a beautiful place.
So I go to Yelp and look at the reviews for BWW and some offer only 1 star. Of course I understand the service could have been bad, didn't like the food, or whatever. But sometimes the negative review can be more a reflection of the person writing the review than the business itself.