Site appears to use aggressive spam techniques such as automatically generated gibberish, cloaking, scraping content from other websites, and/or repeated or egregious violations of Google’s Webmaster Guidelines
Hidden Text and/or Keyword Stuffing
Some of the pages may contain hidden text and/or keyword stuffing
Site appears to contain spammy user-generated content. The problematic content may appear on forum pages, guestbook pages, or user profiles.
Parked domains are placeholder sites with little unique content, so Google doesn’t typically include them in search results.
Thin Content with Little or No Added Value
Site appears to consist of low-quality or shallow pages which do not provide users with much added value (such as thin affiliate pages, doorway pages, cookie-cutter sites, automatically generated content, or copied content).
Unnatural Links to A Site
Google has detected a pattern of unnatural artificial, deceptive or manipulative links pointing to the site. These may be the result of buying links that pass PageRank or participating in link schemes.
Spammy Free Hosts and Dinamic DNS Provider
Site is hosted by a free hosting service or dynamic DNS provider that has a significant fraction of spammy content.
Cloaking and/or Sneaky Redirects
Site appears to be cloaking (displaying different content to human users than is shown to search engines) or redirecting users to a different page than Google saw.
Some pages on this site may have been hacked by a third party to display spammy content or links. Website owners should take immediate action to clean their sites and fix any security vulnerabilities.
Unnatural Links from A Site
Google detected a pattern of unnatural, artificial, deceptive or manipulative outbound links on this site. This may be the result of selling links that pass PageRank or participating in link schemes.
Sumber: The Story – How Search Works