QUOTE: “Some pages load with content created by the webmaster, but have an error message or are missing MC. Pages may lack MC for various reasons. Sometimes, the page is “broken” and the content does not load properly or at all. Sometimes, the content is no longer available and the page displays an error message with this information. Many websites have a few “broken” or non-functioning pages. This is normal, and those individual non-functioning or broken pages on an otherwise maintained site should be rated Low quality. This is true even if other pages on the website are overall High or Highest quality.” Google
Sometimes, Google turns up the dial on demands on ‘quality’, and if your site falls short, a website traffic crunch is assured. Some sites invite problems ignoring Google’s ‘rules’ and some sites inadvertently introduce technical problems to their site after the date of a major algorithm update and are then impacted negatively by later refreshes of the algorithm.
Another excellent guide is Google’s “Search Engine Optimization Starter Guide.” This is a free PDF download that covers basic tips that Google provides to its own employees on how to get listed. You’ll find it here. Also well worth checking out is Moz’s “Beginner’s Guide To SEO,” which you’ll find here, and the SEO Success Pyramid from Small Business Search Marketing.