phranque - 7:58 am on Jun 22, 2012 (gmt 0)

from Google's Webmaster Guidelines:
http://support.google.com/webmasters/bin/answer.py?hl=en&answer=35769&topic=2370419 [support.google.com]

under Quality guidelines - specific guidelines:
http://support.google.com/webmasters/bin/answer.py?hl=en&answer=35769&topic=2370419#3

Avoid "doorway" pages created just for search engines [support.google.com], or other "cookie cutter" approaches such as affiliate programs with little or no original content [support.google.com].

it's pretty clear these are "doorways".
why report them?
they make useful targets...