I'd say in general the people I've seen live have been disappointing vocally compared to their recordings. Cher was pitch perfect but I guess that's because she was miming
. Saw Sir Elton last year and must admit he didn't sound like he did 50 years ago but for someone in his 70s he was pretty good. Must have something for oldies as also saw Burt Bacharach last year and can forgive him his voice at 91 for his catalogue of work and the musicians/singers he had supporting him. Vocally, the best I've seen, queue laughs but it was a great family night out with the wife and daughters, James Blunt.
List of disappointments include
The Jam (vocally From the Jam were better)
Paul McCartney
Cyndi Lauper
Rod Stewart