i can easily tell when an actor is faking a stutter. When i stutter, my facial expression changes, i clench my jaw and struggle to get a word out. I mean no one knows the struggle unless they really struggle, right? So i can easily tell when someone is faking it. Except for Collin Firth in King's speech. He did an amazing that watching him stutter on screen brought my high intensity stutter back for a few months.