Don't be sily Al - that's the way he hears it. It is his interpretation of the music that drives, not the music itself. If it was the music itself then everyone would hear it the same and the way we play or sing the songs would never alter, whereas we know that excellent musicians can interpret songs differently.

Take (not a folk song) the Freddie and the Dreamers interpretation of "If you gotta make a fool of somebody" with the wrenching Bonnie Raitt version

Or take the established practice of doing "Ride On" slower than a snail and compare it to John Barden's driving version.

Or in folk music, consider the previous versions of pretty well everything (folkish) that Fairport or Steeleye recorded with those later recorded versions.

It's the musician who chooses. Do you really think all those songs were in 5/4 before Martin Carthy decided he liked that time signature?

But to go back to manners - it is of course bad manners for someone to stand up and screw up. It is equally bad manners or worse to tell him/her so.

And so to standards. I screwed up "The Derby Ram" badly yesterday(in public). The guitar riff (yes, I mean riff) is not wholly easy, and just as I was having to divide my concentration between that and remembering the start of the next verse, I was tapped (with the best of intentions) on the shoulder to warn me that Ken's ferrets were about to fall onto the floor with their cage behind me (seriously). I lost it big style. I fell off the guitar riff in "Knight William" too (although I got that one back), but I still had non-folkies coming in from the bar next door to listen. I made NO mistakes with "Come Away Melinda" (see, I'm not completely anal about doing only "folk" songs) at the end of the afternoon, and I think it went down pretty well. But if you tell me that I'm going to have to audition, or to have others sit and tell me whether I am good enough or not - include me out of your place. You may think that a good thing, or a bad thing, but I am clear that it is a bad thing and that it inhibits the recollection, assimilation, and continuation of folk song in circles outside the hard core.