Here’re some examples, resources to better understand and fight of hacking and spamming on your website. “An example we often see is hackers using an exploit in a sites database (SQL Injection) or in sites that have unchecked areas for user input (XSS). Run the following site: query (site:.edu free ringtones) and look at the URLs. If you see some trailing parameter like [/?p=ringtones], then your site is most likely hacked,” Google Enterprise blog noted.

Resources: Google Webmaster Central blog post on Hacking, and Spam