,when I started as a floor singer 1971,the competition was tough,nobody ever sang songs with words in front of them.
I can remember going out to the toilet to run through words ,to make sure I had it right,if you werent any good you didnt get a chance to sing the next week,if a performer forgot a word they carried on,we had to learn how to perform,as we were doing it,and that[ imo] is the only way.
I experienced all those things as a newbie performer,but I got up and did it,I practised a lot before I went on,if i played a wrong chord aor sang a wrong word [I let it go ,and made sure I got the next verse right].
making a mistake can happen to anyone,the most important thing is to learn to feel at ease,whilst performing,[this is what the alexander technique is about],throw away your word sheets,if you make a mistake,make it up or make a joke.,carry on,nerves have to be conquered.
on the other hand Iwould never criticise anyone in a club if they were singing with words [if I was guesting,or whatever],Iam not that bad mannered,I am just stating my opinion.