Interesting question. I think of bluegrass as the rock n' roll of acoustic music---a lot of it has a frantic nature to it, and I guess that people who like that sound and that beat might not care much about an evening with Michael Smith. I like bluegrass music...in small to moderate doses. I get weary of the themes (Jesus stuff especially), and the banjo can give me a headache. But I also like other forms of acoustic music in moderation too, such as Celtic especially. But I think you're onto something: bluegrass festivals I've been at have a blue collar family picnic ambiance while the folk festivals often have a hep, alternative, old hippie, college, left wing crowd. While we all might say we like all kinds of music, let's face it, when it comes to putting down one's cash, we're probably selective and the folk and bluegrass audiences are 2 distinct sub-cultures with a little overlap.