I once sat in the front row of a really bad opera about Mary Queen of Scots. It was so bad I could hear the conductor muttering things to the orchestra like, "Let's pick up the pace, I need a drink". And members of the orchestra were giggling. In spite of that they were complete professionals who kept on playing. People in rows further back never knew what was up.
I'm starting to get the feeling professional musicians can keep going through anything. They're all in some way descendants of the guys who kept playing as the Titanic went down.