I am not making this stuff up. It's out there. In a recent article named 'Customer Rage' Is on the Rise, customers are no longer accepting poor service. The article states "According to a Customer Rage Survey released today, 15% of shoppers surveyed who received unsatisfactory service actually sought revenge for their suffering." I found that statistic to be staggering. Read the article for yourself. It pays to be nice, or it may pay to hire security.
Seriously, most people who experience poor customer service will leave for another provider. They will leave quitely, at first. Then they will tell anyone who will listen how bad it was. Sales does not end with the sale. Take care of the customer, during and after the sale.