I've only been multiboxing for a few days now but am loving it.
My Warlock team is ploughing through Westfall at the moment and I've experienced anything from nice long chats about how it's done to the usual profanity and even to people training mobs onto my group in an attempt to wipe me.

I've spent a few hours working on some macros to get my group into formation and dance for the audience, which does tend to improve their reaction, and we all carry a supply of snowballs to launch at the detractors