Yeah, I know who that bozo is. And then he says something like, "Oh, what was I thinking?" Gee, buddy, can you be any more insulting?!
I actually killed that dude and Belethor. Came back to Whiterun after becoming a vampire, and the two of them attacked me in separate instances. Took 'em both out. Best part? Belethor's shop is no longer open "for business" to me and the dude's wife always utters something smarmy like, "I hope you rot out in the wilderness" every time she sees me. So I tend to pickpocket her every time she hurls an insult.