According to Google, “Sometimes a page may look clean to you but hackers often inject content that only search engines can easily see. 'Fetch as Googlebot' shows how your page looks to Googlebot (our website crawler) so use it to identify and clean up hacked content.”
Learn more about Fetch as Google: http://goo.gl/C15CyK.
Fetch as Google option allows only 500 URL submissions per week per account. You can view the previous tips by Google here:#GoogleRecon Tip 4: Use Fetch as Google to Identify Hacked Content!,