I havent worked exactly as a waitress, but I have worked for a good time (about two years total, in different places) in customer service on the phone in two languages. When I attended in my second language, I would kinda try to hide my stutter, blaming it on the fact that I was speaking in my second language. But I also worked using my first language and I didn't have a excuse there. Of course I have found rude people on my way. others would pity me, which felt worse, and others were genuinly worried that their phone was broken or something like that. But I never got fired for stuttering or anything like that. In fact, I even got positive feedback from the customers fairly often (which in customer service equals a bonus for good service) and every time I stopped working in a job was because some better opportunity came along.