My guess is it's the sheer number of plugins in your wordpress installs, including plugins like WPRobot and a few other Autobloggers. Those same autobloggers are clearly against the TOS:
* Auto Generated Content: Sites that use scripts to automatically generate content are prohibited, this includes but is not limited to AutoBlog scripts and anything else that automatically generates websites for SEO or other purposes.
This is under the "not allowed" section of the TOS.