Business Week published The Customer Isn’t Always Right. The article is worth reading in it’s entirety, but can be summed up by the last paragraph:
That, in a nutshell, sums up why you should always take the voice of the customer with a grain of salt. Customers can offer valuable and insightful information, to be sure, but they ultimately work for themselves, not you. There’s nothing cynical or antagonistic about that; it’s simply the way the marketplace works. The more you know about their interests, the better you’ll be able to act in your own interests, keeping the invisible hand working for us all.