Because of the filter bubble highlighted by Eli Pariser, there is massive opportunities for SEO companies to trick their customers into thinking they have got high up in the SE results, when all they are seeing is their filter bubble!

https://www.ted.com/talks/eli_pariser_beware_online_filter_b...

The last link someone clicks on, is usually the right link to associate with the search term for future users. Its not hard to make a search engine!

I'm not a Robot!