This might seem weird, but I find stutterers to very often be really charismatic people. I'm not a stutterer myself, I came across this post on Explore New Subreddits, but I've often noticed this about stuttering people. It might possibly be because speaking quickly is often used as a method of coping with stuttering and fast-talk is one of the signs of charisma. I'm not sure if that's the explanation, best I can guess.