What Yahoo Considers Unwanted:
Some, but not all, examples of the types of content that Yahoo! does not want include:
Pages that harm the accuracy, diversity or relevance of search results.
Pages dedicated to redirecting the user to another page (doorway pages).
Multiple sites or pages offering substantially the same content.
Sites with numerous, unnecessary virtual hostnames.
Pages produced in great quantities, which have been automatically generated or which are of little value (cookie cutter pages).
Pages using methods to artificially inflate search engine ranking.
The use of text or links that are hidden from the user.
Pages that give the search engine different content than what the end user sees (cloaking).
Sites excessively cross linked with other sites to inflate a site's apparent popularity (link schemes).
Pages built primarily for the search engines or pages with excessive or off-topic keywords.
Misuse of competitor names.
Multiple sites offering the same content.
Sites that use excessive pop-ups which interfere with user navigation.
Pages that seem deceptive, fraudulent, or provide a poor user experience.