Well I two-boxed (manually, two-keyboards, two systems) from day 1 of WoW.
No one ever said anything to me.

I upgraded to a third account, and then decided why not go 5 if I'm moving up anyway?
Since then, I get a lot of comments, maybe 3-4 per playing session.
75% are positive, but 25% are negative.
I seem to get a lot of people /spitting on my toons.