There are seo companies that get average results and there are effective SEO companies that consistently get the best results possible for any given client. This is because seo is about generating content that will be recognized by search engines as the best in the world, and not much else. SEO companies used to employ tricks to get the results that they wanted, and now they have to generate better content than everyone else. Search engines like Google have ways to detect tricks and stunts that are designed to get higher rankings, and they penalize the websites that employ them. They also look for the websites that have created the most powerful information, and are the ones that people will sue as a reference for that information. These are the websites that the search engines are going to put at the top of the results, while everyone else gets pushed to the bottom.