Dishwasher was a menial job, often found in restaurants. The clone commando Gregor once worked this job after getting amnesia.
Someone who worked as a dishwasher was expected to wash dishes and might also perform other menial labor such as taking out trash.
After the clone commando Gregor lost his memory and ended up on the planet Abafar, he was taken in by Chef Borkus of the Power Sliders diner and given a job as a dishwasher for nothing more than room and board. He seemed to perform the job with reasonable competency, but showed no great enthusiasm for his work and gladly left it when he was informed by Colonel Meebur Gascon that he had been a clone commando.
A dishwasher first appeared in Star Wars canon in Star Wars: The Clone Wars in the episode "Missing in Action."