My answer: I have no idea. We don't do traditional folk, and we don't do political folk. There's not a guitar player to be found in our band, so we don't sound like stereotypical folk. My best guess? We're acoustic (or at least my keyboard competently mimics an acoustic instrument), and we're interested in participating in an event that has the word "folk" in it ... and that's good enough for them.
We got a good response when we played, so it seems to have been good enough for our audience as well. Wahoo!
I think "Folksinger Song," by local artist Brad Fritz, sums it up nicely:
I really don't know if I am a folksinger
But I sure do like singing for folks