How to use "Fetch as Googlebot", part 1Webmaster level: IntermediateHas your site ever dropped suddenly from the index or disappeared mysteriously from search results? Have you ever received a notice that your site is using cloaking techniques? Unfortunately, sometimes a malicious party "hacks" a website: they penetrate the security of a site and insert undesirable content. Sophisticated attackers can camouflage this spammy or dangerous content so that it doesn't appear for normal users, and appears only to Googlebot, which could negatively impact your site in Google's results.In such cases it used to be very difficult to detect the problem, because the site would appear normal in the eyes of the user. It may be possible that only requests wi...

Article source: Google Webmaster Central Blog.