Although SEO Moz is a very solid site for SEO advice and such, I'm a bit skeptical about a tool promising to asign a score to your site.
There are literally an infinite amount of variables which affect SEO today and as such it is impossible for a software program to emulate all the variables and spit out a simple score. Google even has recently begun punishing webmasters who overdo the SEO - so following the advice of these tools now actually might cause more harm (although in the past they were helpful for basic guidelining).
When it comes to SEO - the golden rule is to provide quality content and the links will come and so will the crawlers. If there is any hint of gaming the system or forcing the process, Google and the others will detect.
This page from Google actually should help point you in the right direction: http://support.google.com/webmasters/bin/answer.py?hl=en&answer=35291