I freelance dealing with these kinds of problems, and I wanted to correct one thing.<p>The article states that the message "The site may be compromised" appears in Google result pages when "the site has been hacked and complete control is taken by some third party without any owner’s permission. Anyone can contact the webmaster and help them to resolve this issue."<p>That's not true. It means that Google has seen content on the site that doesn't meet Google's standards - in other words, there's spam on the site. Usually this means the site is hacked and spam content has been added through various means:<p>- obfuscated code added in legitimated script files, which only displays when the visitor's user-agent string is a search engine bot<p>- a script that generates tons of static files with keywords it receives from a distributed spam network<p>- links and text in invisible page elements added directly to a database (like Joomla or Wordpress)<p>I've also seen the occasional instance of this warning when there was simply a lot of spam on a site (e.g. in forum posts). Once you clean it up, you do have to use Webmaster Tools to get Google to reconsider and revoke the warning. It usually takes one to two weeks.<p>By contrast the "This site may harm your computer" warning refers to pages with content that attempts the installation of malware. You can also use GWT to clear this warning and it's much faster - within a day, generally.