They’re actually worse than bill collectors. According to the article, Righthaven is not a law firm and acquires copyrights strictly for the right to sue infringers, so its standing to sue has been an issue in most of its contested cases. Apparently, they actually want people or blogs to post their copyrighted articles so they can sue them.
Fair use allows you to quote from copyrighted works for educational and public knowledge purposes, to a certain extent. Of course the question is when Fair Use becomes copy right theft, that’s what the courts decide.