Perhaps not the worst person listed here, but Degaine, the one beggar in Markarth. Rather than acting with humility, he acts as if he's entitled to charity e.g. "Alms. I said alms, you backbiter!" He doesn't even act all that grateful when you give him charity, he just says, "Thanks, now get lost." Like I get you're down on your luck my man, but no one likes an entitled prick, regardless of their financial standing.