Well, so far only 1 person has been serious about it (my friends keep making chars and shouting "you're a bot!" at me for laughs), a low-lvl hordie who kept going like..

"you're botting, right?"
"no, I'm dualboxing, 2 computers and 2 accounts controlling 2 chars"
"yes but u can't do that, so really you're botting aren't you?"
"no, I got 2 arms so I can in fact have 1 hand on each of 2 keyboards"
"yes, but you're botting"
"whatever"

Then I told one of my very alt-and-accuse-addicted friends about it, and he started on something I must admit I would've never thought of:

"The capital of Denmark is Copenhagen"
"huh?"
"The capital of England is London"
"what?!"
"The main export of Iraq is Oil"
"ffs noob! You're reported!"
"For what?"
"shithead" /ignore

Really I'd suggest using that on anyone who claims to know wether or not you're botting better than you do. With some luck, a GM will look at the chatlog and say "yeah you're absolutely right, you were waay out of line with the insults so I'm giving you a 1-week ban. Thanks for reporting yourself, it's rare that happens".

Haven't happened yet, but there's always hope.