These quality guidelines cover the most common forms of deceptive or manipulative behavior, but Google may respond negatively to other misleading practices not listed here (e.g. tricking users by registering misspellings of well-known websites).
It’s not safe to assume that just because a specific deceptive technique isn’t included on this page, Google approves of it. Webmasters who spend their energies upholding the spirit of the basic principles will provide a much better user experience and subsequently enjoy better ranking than those who spend their time looking for loopholes they can exploit. If you believe that another site is abusing Google’s quality guidelines, please report that site at https://www.google.com/webmasters/tools/spamreport. Google prefers developing scalable and automated solutions to problems, so we attempt to minimize hand-to-hand spam fighting. The spam reports we receive are used to create scalable algorithms that recognize and block future spam attempts.