Audiences at all the folk clubs I've been to have always been incredibly supportive of the singers and musicians. That is a good thing in many ways but it does mean that singers who only ever appear at folk clubs might genuinely never realise that they're not great. After all, they always get listened to politely all the way through and receive a round of applause at the end, no matter how good or bad the performance. Compare that with a typical comedy club where you're left in absolutely no doubt whether or not someone has died on their arse.