When pages are removed from a search engine’s index specifically because the search engine has deemed them to be violating their guidelines. Although procedures are starting to loosen up somewhat, typically a search engine will not confirm to you that your site has been banned or why it has been banned. If you knowingly did something against the rules (written or unwritten) that got your site banned, you can probably clean up your act and get back in the game. We hear stories, though, from time to time of companies hiring Search Engine Optimization companies that deliver great, fast results, leave town, and then their website mysteriously disappears from the rankings. Google won’t tell them why their site got banned, so the company ends up left out in the cold unless another company can come in and backwards engineer the issues, unravel the work, and get the search engine to reinclude the site.