Recently on a franchise related internet community site, the question was asked: "What is the most important thing I shouold do when investigating whether to purchase a certain franchise?" 

To me, as a franchisor attorney, the answer is easy - when investigating any franchise system RANDOMLY select and talk to as many existing and former franchisees in the system as possible. My rule of thumb: do so until you find at least three that are not happy either with their investment or with the franchisor. Even the best systems have a few franchisees who are not pleased. Find out why. On the other hand, bad or poorly run systems have many unhappy and vocal franchisees.

Also, always ask " who else should I talk to?"

This important first step costs virtually nothing and gives you some of the most important information you can obtain and from sources you can believe. And, don't make the mistake of only contacting franchisees in your local area or region of the country.