I read up on the methodology used to determine how jobs rank and it seemed that jobs requiring physical energy were determined to be more negative. That is, the more energy required the more likely the job was to be in the "worst" category. This methodology seems flawed to me. What if moving around is something you love. Some people would die in some of the less active jobs mentioned as "best" jobs. I think whether your job is the best or worst depends on how you perceive and feel about the work you are doing. I understand that some of the jobs described as "worst" are dangerous, but does that always mean that the person doing them is unhappy? What if they felt miserable as an accountant or statistician?
It seems to me that people would be better off choosing a job based on their strengths-- even if those strengths happen to be in one America's worst jobs. A book like What Color Is Your Parachute? 2009: A Practical Manual for Job-Hunters and Career-Changers
would be a more helpful way of deciding on a career than ditching a job choice because CNBC or some study group called it "the worst job in America."