Joiners are not sitting in judgement on anyone. Shushers are.

Wrong again, Richard. The joiners in are the ones sitting in judgement - they're the ones who are doing the violation. I known young inexperiened singers giving up on Folk Clubs entirely because their confidece was shattered by some buffoon thinking he was no doubt doing them a favour. When it happens to me it ruins my night because I'm an jolly old cove who hates conflict - it depresses me to have to tell someone to shut up. Depresses me even more to see that look of hurt in their eyes as they assume the role of Victim, which is maybe another reason why they do it - because they enjoy being the Victim of a situation they themselves have instigated.

No One EVER convince me that when Bob and Ron's Great Great Whatever Grandfather was singing in the pub he was helping to estabkish a Semi Religious Art Form !   

Well, on what sort of grounds do you base that assumption because in my experience of Traditional Folk & Ballad and the Traditional Singers thereof I see something very serious indeed. Great entertainment has to be serious - it's as serious as your life. Even clowns have to take it seriously; Stan Laurel spend entire days editing the film stock just to maximise the effectiveness of his art. Traditional Folk Song is an art form; to do it justice we must approach it with due reverence and study it, listen to the old singers, read up on Broadsides, trawl the archives, get into the blood and bones of the thing; become possessed by the lingering ghosts and haunted into sleepless nights in utter terror at what we're dealing with here in our role as Folk Song Mediums which is a huge undertaking and a whole lot more than mere entertainment.

As for religion, for a Godless irreligious hedonistic oik such as myself then The Folk Club is one of the few places where I'm likely to have a genuine Spiritual Experience these days.

I'd definitely encourage people to at least make an effort to practice their instrument and the pieces they want to perform,

Absolutely 100% spot on. I understand these days they're singing songs off their Kindle screens. WTF?

A wee anecdote. There was once a singer of my acquaintance who made bold his anouncement that he had a variant of The Cregan White Hare, called The Bonny Black Hare. This guy is a real moralist Christian and it was obvious he hadn't even bothered to read the words before getting his iPhone out & scrolling through the text as he sang them. He's someone I like a good deal actually & there I was trying to catch his eye, shaking my head, mouthing No, No!, but all to no avail. He sang the song in complete innocence, slowly becoming aware of its metaphorical nature as several Folk Club members doubled up in helpless laughter. A classic really. But a lesson learned, I hope...