How you measure a SEO Company as SEO Specialist?

Over the years we are hearing many SEO Services companies claims they are SEO Specialist, My question how you even they rate thyself as SEO Specialist? we all know that SEO has no shortcuts system or  even we don't know how & why search engine like Google rank particular website or keywords. Apart from Google Engineer Matt Cutts, Google  evaluating multiple changes over the year for filter better search results. http://www.mattcutts.com/blog/algorithm-change-launched/

When Some  SEO Services companies claims thyself as SEO Specialist you can sort them via some simple way.

• Are they engage & answer with their followers at social media & forum?
• Are they have any Blog site under their main/services website?
• Are they regularly post content on their blog?
• Are they participate to commenting on similar Blog?
• They have many client testimonial with client address?

If above all answer is YES for any SEO Services companies, you can rate them SEO Specialist & can take their services