Different stages maybe kote. At a really early stage when you don't have too much to show, not many strangers will want to listen. You'll need friends at that point.
Agree with messel. Beside stranger wanting to listen or not your new product I believe its about "shut up and do it" finish your 1.0 version then show around different kinds of people (tech and non-tech, biz and non-biz related people)and try to get a rich feedback from them
I love presenting to strangers as a way to get feedback free of relationship-related noise. I rather have strangers poke holes at my business than have relationships ignoring them.