After all, everybody KNOWS when they're still crap
I don't think that's true - and that is one of the roots of the problem besetting folk in the UK. Web forums aside, people in the folk world are accommodating, non-judgemental types who would rather drink stale beer that actually tell someone that they're crap.
It means that the folk circuit is a very broad church indeed, encompassing some absolutely brilliant amateur performers and some utterly dreadful ones - and all of them are received with the same polite applause. I long for the day when I see the same robust abrasiveness one sees on the comedy circuit, or the blues circuit, where crap performers are told by the audience that their crap, and to come back when they're not. OK, maybe no quite as abrasive, but...