Mmmmm, OK if the session is billed as 'anything goes' however I was once involved in trying to start a trad session in our area, but we had one person who played David Bowies Space Oddity. I tried to save the trad session by pointing out that this wasn't really appropriate material, and warned that if we went down this road, the trad music session would be in danger of being taken over by rock guitarists, I was 'told off'. I gave up and left it to those who 'knew better'   LOL Unfortunately my prediction came true and there is no more trad session. Nuff said!