When I google for certain questions, or problems I run into I would sometimes run into 'archive' sites - these sites contain forum questions or information from other sites that are extremely poorly formatted, and are copies of the well formatted original posts from various forums. An example of one of those sites in mail-archive.com and various similar sites.

Can anybody explain to me why those sites exist and how come they don't get banned from Google (since all they have is copied content that is really poorly formatted by bots)?

Thanks!