I remember once in Galway (Crane Bar) when a Dutch chap started singing. He was not the greatest... mainly because of his hesitating English and pronunciation, which affected the songs (he might have been great in Dutch). That said, everyone paid him the compliment of listening. I sang a reply. He then tried to sing Rocky Road to Dublin and I think we all felt every bump of the rocks! My firend, who was leading the session, told me not to sing another after him.

I thought it was just to let the chap have his moment and not to show him up. In retrospect, I think it was more that she didn't want the rest of the pub to have to sit through another of his songs.