I first experienced this when doing customer support for an online music store I built. A technically illiterate customer would email me with a simple question like, "How do I download my music?" even though the download links are right there. When I answered them with detailed instructions within 5 minutes, they would become evangelists for the store by recommending us to all their friends because of the "amazing service".

If those customers had spent just a minute figuring out how to find something they downloaded, I could not have helped them and they would not have become as loyal.