SEASON 1
From the ep, "Junklantis", it's pretty undeniable that Garbageman has no legs at all or rediculously undersized ones.
Which would make sense considering the never-completed (due to its controversial nature) Season 5 Episode "Nightmares Recycled," in which it was to be revealed that Hun and the Garbage Man were conjoined twins at birth. My grisly guess is that GM was snipped off and thrown into the trash...