My positively trained dog refused a recall and got hit by a car. While I bet there are cases where every one of the above statements is true, the fault lies, I'm afraid, with the trainer, not the method. This article explains the truth behind the most common clicker training myths. This is an argument frequently made by people who train their dogs for competition obedience. They can't take clickers or treats into the ring, so they're afraid their dog won't perform.
Food is a marvelous training tool.
Dogs are born needing and wanting it - it's a natural reinforcer. But, like any tool, it must be used properly. Teach the obsessed self control. Some dogs, often those who are unaccustomed to much variety in their diet, become a bit too food focused. Some basic attention exercises will help these dogs get their minds off the food and back on the task at hand.