01 Jun 09
25 May 10 7:19 am
Yes, "duplicate content penalty" does apply to directories and comments, too.
Duplicate content as described by google are "substantive blocks of content within or across domains that either completely match other content or are appreciably similar." While most may not be deceptive in origin, there are cases where "content is deliberately duplicated across domains in an attempt to manipulate search engine rankings." If google sees a page that has the intent to deliberately manipulate rankings, it makes appropriate adjustments in the ranking and indexing of the page involved and it does not matter if the content is in directories or comments.
Google says that "buying and selling links is a normal part of the economy of the web when done for advertising purposes" but "buying or selling links that pass PageRank is in violation of Google's webmaster guidelines and can negatively impact a site's ranking in search results."