Thirty years ago, it was estimated that an unhappy customer will tell 10 people about the poor product or service he or she believed they received, and will ultimately cost you at least 100 potential customers (clients or fans). Maybe less, seldom more; but that is what we call 'history' and EXTREMELY OUTDATED STATS. With the invention of technology, the internet, social media, and KEYBOARD WARRIORS the number of people that can 'hear about' BAD reviews are THOUSANDS to potentially MILLIONS!!
Today, the generation of passive-aggressive attitudes that grew up in the 'I want what I want... NOW' are often implusive, knee-jerk reACTING, expecting cheap and immediate gratification. Especially if it involves technology. They each have computers and smart phones, and really know how to use them. Facebook, Twitter, Yelp, Google Reviews, and the variety of other passive options can be used to COMPLETELY TRASH YOU! Many don't allow bad reports to be removed, regardless how false, wrong, mistaken, or emotionally charged they might be. Ripoff Report and Consumer Affairs are about the only ones you can 'at least' respond to (but still can't remove them).
The average unhappy customer can reach hundreds to thousands, quickly and easily with passive activism. If they are real smart, pro-active, and their story is good, well presented, it can reach tens of millions in the blink of an eye. (See "United Broke My Guitar" by Dave Carroll Music... it's gone viral, in the billions of views... complete with TV and speaking appearances, videos of the song, and even a book). For those that haven't seen it, the video is at the bottom of this page, as an example of what an unhappy customer truly wronged can really do to the company that doesn't step up and take responsibility for the wrong(s) committed.