I used to be a teacher and I never stuttered in front of students. I always explained it to people this exact way. I wasn't me when I taught, I was the teacher, a character. And that character doesn't stutter. I don't feel responsible for what people think of that character because it's not me. Before that I had customer facing jobs and the same thing. I'd slip into a customer service character and wouldn't stutter. Then I go home and stutter all over the place.