I give singers and musicians who are in their early stages of performance career a certain amount of lee way,after all they have to start somewhere,something veterans of forty years of performing sometimes forget.I am less forgiving to those who make little or no effort to improve.Club organisers are sometimes a little too kind to non improvers and should encourage them to get better or ditch them.
With regard to crib sheets I have no objection in principle,I have seen excellent performances by users,it's how they are used that counts.The crib sheet used properly is unnoticed,it's the incompetent performer who falls over his act in spite of his crutch that annoys me.