It is particularly bothersome that I can hear it the way I want to say it in my head, but feel it go wrong the moment the words come out of my mouth. This means that the tone of the message that I'm trying to get for my character say comes off quite differently than I intended. Thus, my character sometimes comes out differently than I envisioned.
Still, as the entire game is meant to be in good fun, these horrendous accents can be a source of humor in and of themselves. It's having fun that really matters.