Black hat SEO is doing illegal means of search engine optimization or fooling search engines to get better page ranks on search results. Usually, these tricks are short life and will be terminated by search engines by an update of their bots or algorithm. Better not to go for black hat SEO tricks if you are on making benefit of your website or blog on a long run. Most probably spammers with deep niche content are using these illegal tricks as they are not bothered about future rankings. Instead, they will make the most out of their pages in a short time.