A degenerate
A person who's so low they live in the sewer. They're like a worm. They have no dignity.
He's a degenerate. He eats out of the trash and smells like a dead cat.
My friend's friend is a degenerate. He lives in the park and steals food.
I saw a degenerate on the street. He had no clothes and was eating out of a dumpster.