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Why does this spam page have such high authority? Andrew's analysis of this subject is right on the money. I will add a couple important points: 1. DA / PA are SEOmoz metrics. They are independent metrics created by SEOmoz. These metrics are not endorsed by Google. 2. DA / PA offer insight into a a web page's backlink profile without regard to any other factors. As I look at the SEOmoz site today, it has a DA of 95. If SEOmoz was to create "The Ultimate Spam Page" and filled it with pure spam (i.e. viagra, buy links, free nude pics, etc), that page's DA would still be 95 because DA is a sitewide metric and applies to all pages on the domain, irregardless of the content on each page. If this web page earned links from SEOs and other websites then the page could have a PA of 63 or more, just like the page you shared. When you refer to the web page as "spam", you are referring to it's content which has nothing to do with it's DA / PA or backlinks.