funny but some musicians feel exactly the same about off key singers 'joining in' in F and five eights or G and a quarter and trying to pull the musician off key. Personally I just like to see everybody enjoying themselves rather than just a few playing/singing at what they may consider to be some sort of concert standard and will happily try to adapt playing to any 'uninvited' (in a session!!!!!) singists. Or should we all be permenantly po faced and deadly serious?!!