Source: https://moz.com/blog/spam-score-mozs-new-metric-to-measure-penalization-risk
Spam score works by collecting the amount of spam flags from a subdomain. These subdomains are crawled by Moz web index aka Mozscape. Spam score can be accessed using OpenSiteExplorer which includes pages and subdomains linking to your site. This tool is only available for PRO subscribers but you can also test it with a free trial.
When to use Spam Analysis?
– If the site is targeted by negative SEO
– Unnatural link building practice
– Disavowing links
– Link audit and evaluation
Some Spam Flag details that you should know
– Low Moztrust or Mozrank which is an indication that a site is not trust worthy
– Diversity of links is low
– Unnatural ratio of Dofollow and Nofollow links
– Low amount of branded anchor text used
– Thin content
– External and internal link ratio (too many outbound links or too few internal links)
– Ratio of anchor text and content inside the page