I think you should talk/listen to them as you do with any other person who doesn't have a stutter. I think it's a good thing to not make the stutterer feel like they're different in any way. If you usually make eye contact, nod, smile at the things one is saying, or whatever, you can do that! I think there's a difference between smiling at someone when they are talking and laughing in a derogatory manner. You have to make sure you're not doing the latter. Be sensitive is all I am saying :)