Both black hat and gray hat SEO methods violate or skirt search engine guidelines by using tactics that trick the search engines. Unethical tactics like submitting a site to a multitude of low-quality directories, keyword stuffing (overloading keywords onto a webpage), cloaking (showing one page to the search engines and another to humans), and page swapping (changing the webpage entirely after it has been ranked by search engines) put your site at risk. They can damage your brand reputation, make your site vulnerable to search engine penalties, and could even get your site banned altogether from the search engines.