"In other words, I suspect that clubs that don't have a problem with quality are also clubs where traditional material dominates and where participation's expected; that way, the standard maintains itself, or is maintained by the regulars."

Pip. I really don't follow your logic with this one...... I've seen lots of very good and very bad performances of Traditional songs and equally lots of very good/ very bad performances of self penned/ cover songs. I think around here I've seen more people using song sheets for trad songs than anything else.

I think to try and assert that people take more care over trad songs than others is well, tosh, quite frankly! There are people out there who will murder anything.