Usually, happy customers do not talk to anyone about your business. On the other hand, unhappy customers will be sure to talk to everyone about your business and their problems with it. This may include complaining to their friends, neighbours, and anyone else that will listen about your exorbitant prices, careless workmanship, and horrible customer service.
As a business owner, your goal is to turn every unhappy customer into a satisfied customer. He may not tell everyone about his satisfaction but at least, he will no longer be a constraint by further spreading his bitterness against your brand.
An article posted at yfsentrepreneur.com talks about how you can take advantage of this situation. The article can teach you how to deal with your unhappy customers and learn from them.
You can read the full article here: http://yfsentrepreneur.com/2013/07/23/9-ways-to-deal-with-unhappy-customers