There is no down side to helping them do it – in addition to gaining better qualified customers and repelling potential customers, who would not be happy with your service, you can learn how to improve your offering, product or business practice. In addition trying to silence unhappy, reasonably or not, customers you would risk your reputation much more, as they have many outlets in social media that you cannot control. There are many examples of companies that tried to manipulate and fake customer feedback. They ruined their reputation, hurt their business and even were penalized by government agencies. I wrote about these in my blog http://blog.amplifiedanalytics.com/2010/01/how-to-get-your-customers-to-market-your-products/.

The voice of Customer has always existed, it is much more amplified now and therefore can be effectively measured and managed.