John Caddell of Caddell Insight Group explains why listening and allowing customers to comment is important in "Customers are talking -- candid customers won't give you 100%."
When the community (fill in the term that is appropriate: clients, customers, students, etc.) expect you to be very good at what you do, they are not going to give you a perfect ranking. Instead, they are going to point out weaknesses. Most weaknesses can be addressed by making improvements--not by making excuses or debating your customers.