So maybe this is just a me thing, but when I’m talking to someone who has an accent at some point I start thinking in that accent. I have to think about not speaking like that, it would sound really insulting. I do it with TV Shows, when I watch British Sitcoms or Doctor Who I start to effect that sound, until I realize that it’s happening. Australian, same thing. I have a Russian ballet teacher and every time after class for at least half an hour I have to stop myself saying things in a bad Russian accent.
But the thing about being in costume is that if i want to talk in a bad British accent or add a Southern Drawl, totally cool. I can play with it and have tons of fun pretending to be whoever I want.