The following is from Marc Benioff’s Behind the Cloud: The Untold Story of How Salesforce.com Went from Idea to Billion-Dollar Company-and Revolutionized an Industry:

To be effective, a company’s brand must be consistent.  A company must use its people, its products, and its messaging to consistenty reinforce the same positive points it wants to demonstrate.  A delivery service that promises to meticulously care about your packages cannot have dirty trucks.  A bank that says it cares about its customers can’t have twenty people waiting in line with only two tellers on duty.  Brands cannot break the promises they make.  Broken promises destroy customers’ trust.  That ruins everything.