Search engines are constantly tuning their algorithms in order to deliver better and "cleaner" search results for the users.
Any Search Engine algorithm is their trade secret and they are not planning on sharing it with SEO companies. They generally suggest “to create a good website and let the search spiders find it”. All their guidelines and suggestions point to improving your site content and usability for an average website user. They penalize sites for using any kind of deceptive tricks. That makes perfect sense – sort of like a natural selection...