Muggy is programmed to be obsessed with cleaning coffee mugs, and fully aware of this obsession as well as his inability to stop or do anything about it. In an ironic way, this not only shows his advanced design compared to almost all other RobCo robots, but also Dr. 0's ability in robotics and artificial intelligence. Muggy harbors a deep-seated resentment of Dr. 0 for creating him which deepened after 0 became a Think Tank. Usually, when given a mug, or plate, he cleans it or shatters it.