How to Spy on your Competitors PPC Strategies

I get asked this one very regularly by clients. How can I find out or at the very least get an educated idea of what my competitors are doing with their PPC spend. This is a great idea to help you with this concept.
http://searchengineland.com/tips-for-sp ... tors-89988
http://searchengineland.com/tips-for-sp ... tors-89988