That's pretty funny because I had formulated the exact opposite theory. I'm a financial analyst for a Fortune 500 company and my friends and associates who use the 4S are business professionals. For the most part, we all give Siri a collective thumbs down. Based on my circle, I figured that those who may actually like Siri are teenagers.
And Siri understanding what I've said, is only half the problem. And I have no accent and enunciate well. It is more the logic that is employed by Siri that is "off".
I've come to the conlcusion that anyone who says they never or rarely have problems with Siri understanding what they say, is lying.
Well we can agree to disagree, agreeably. :-) I am NOT lying. Many "professionals" don't have the time to "tinker" with a tool until they master it. I did. And Siri delivers all Apple promised. Now is she "perfect" - no way. Did she change the way I do my daily administrative work? Oh yes! Changed it forever. I haven't needed my admin assistant to do anywhere near as much as she used to. But in the end everyone has their own opinion. The Apple report is pretty stunning though - 87% of people are accessing Siri daily? Wow. That seems to be a "real" tool people are using. And we ARE in agreement that kids use it as a toy.