If you're stuttering really badly or in a touchy situation like a cop stop, telling them you stutter isn't a bad call. Come to think of it, just on Monday this week I had one of my rare bad interactions from stuttering. I do several/dozens of interviews a day for my job, and 99% of the time people don't mention the stutter or act differently at all. Once in a while though you get what happened to me on Monday. The woman on the phone was like "why are you speaking like that? I don't understand you, why are you doing that?" and I told her I stutter, and she didn't say like "Oh, sorry" but said "I'm too busy" and hung up on me! It actually gives me a bit of a rush when people are rude to me though, haha. I think I was treated too nicely as a kid and now I kind of get off on it.