Back in the 'Bad Old Days' when I was between carreers I was on the committee of a small folk club which had a SERIOUSLY physically handicapped floor singer . At a Committee Meeting it was raised that as he could barely see , and and his diction was NOT perfect he should not be allowed to sing .
This was outvoted , and it was decided that he would be on the singers list very time he came , but would NOT be over used OR used as
an early spot every time .
One thing that struck me was that he was ALWAYS pitch perfect - If he sang a song in F , it was in F every time .
Encouraging people to 'have a go' is , IMHO , part of the appeal of the UK Folk Scene .