In Search Engine Optimization there are many aspects that are needed to effectively optimize your website for search engines. It is important to include these different aspects and avoid companies that use less ethical means of promoting and optimizing your site. These less ethical means will only hinder your websites performance as they are generally deceptive and disapproved by the search engines.
'Black hat'' SEO, is the side of SEO that is to be avoided it is generally deceptive and designed to trick customers and search engine crawlers alike. Methods such as cloaking links and mass linking will lower your search engine rankings in the long run and frustrate and annoy your visitors and since these are your potential customers it really does not pay to frustrate them.