It varies a lot by server I'm assuming. I've got 5x 70's on Blackhand and no one hates on me... I'm also the guild leader of a prominent guild who's always had good relations with most of the server... that may help in it's self.

My guild accepts my hobby, the folks I ran into while leveling most often were cool with it, a few zomghax here and there, but nothing suprising or overly rude...

My favorite to date is the guy who told me it was illegal to have more than one account at all... I thought "Gee, and Blizzard has the character transfer service why then?"