Seth Godin, in This is Marketing:
Here’s another difficult exercise, one that stretches the empathy muscle of a typical marketer: Those people who don’t buy from you, the ones who don’t take your calls, who sneer at your innovations, who happily buy from a competitor even if they know you exist . . . those people . . . Why are they right? Why are the people who don’t choose you correct in their decision to not choose you?