Hard to say which job was the worst.
My first job was as a scullery maid in the galley of a pirate ship. Oh, sure, there was plenty of adventure and pillaging- for the men, that is. I, on the other hand, was obliged to toil belowdecks in the noisome galley from morning till night...except when I had to wait upon the captain in his cabin, but that's a story for another thread.
Then, owing to my fine work history on the ship, and with a glowing reference from the captain, I then obtained employment at what was supposed to have been a spa. It turned out to be a leper colony, however. Through much hard work and perseverance, I rose through the ranks (well, really, all my coworkers were dying off) to become the chief cook. The work was enjoyable, but it was hard, especially when everyone around me was always falling to pieces.
Some time later, I was offered work at a ladies' corset shoppe. This could have been a pleasant change from kitchen work, but I had not counted on other women's vanity. Every day, large, fleshy older ladies would demand that I sell them the same model of corset that I wore, so they could be as thin as I. How could I possibly explain to them that my slender frame was due, not to a finely made corset, but to the array of diseases I carried with me from my previous jobs? I'd developed a bad case of rickets, and a milder case of scurvy, whilst on the pirate's vessel; later on I acquired dengue fever and malaria at the leper's colony. As a result, I barely tipped the scale at seventy pounds. My customers grew quite irate when I was unable to help them look as frail as I.
All in all, though, the absolute worst job I ever had was the three days I lasted at Wal Mart.