Google has launched a tool on the market, with the maliciously used or bad links calculation can be removed from the rankings: the “disavow links”-Tool. Is to find the tool in webmaster tools. Google gives an insight into the workings of the tool on the hotel's own blog: Google blog disavow links article tools.
This tool was necessary, because some SEO are specialists on the idea, the competition to devalue, by one so-called “Russian links” bought.
This evil SEO method (Black Hat SEO) works, that one by a poorly gerangten page (best violence, Six, etc) sets a link to the competition. This link causes the Page rank algorithm Google to devalue the competition pages and own page to promote.