I saw Frank Sinatra in 1995/6 in Frankfurt, Germany. He was croaking through some of his songs, and forgot the lyrics on a few others.
He even admitted he was getting too old...
I'd rather had remembered him from his glory days.
The performance was awful. Even then, at JFK Stadium, I knew it was awful.
Years later I was commenting on this point, which was reinforced by Zeppelin not allowing their performance to be released on the box set. Then someone said to me "...but you got to see Zeppelin..."
I don't complain about that performance anymore.