It's an insulting term for scruffy looking people who are presumed to be homeless or drug-using.
The reason it's contentious is that one person uses it, someone else objects to it, people take sides along left-vs-right lines, and the thread devolves in to a shouting match.
The reason it's contentious is that one person uses it, someone else objects to it, people take sides along left-vs-right lines, and the thread devolves in to a shouting match.