In late 2007 Google officially announced that so-called paid links are outside its webmaster guidelines, and asked webmasters to report paid links they find on the Web via a special form. Fast forward to 2011 and you’d expect that paid links are long gone, like stuffing meta keyword tags or inflating keyword density on page. They aren’t.
There is even a surge of interest in buying links after many large brands have been caught using this technique successfully to manipulate Google’s algorithm for months.
These large brands are not alone; indeed, even Google itself has been sponsoring sites that link to it without using the nofollow attribute required by the Google webmaster guidelines. So it’s no wonder that in this world where some people are more equal than others, many webmasters resort to buying links from text link brokers who are still more or less openly selling them.