It's Time

At some point in time, a singer - any singer - reaches a tipover point where the audience enjoyment at seeing/hearing that famous person is more than counterbalanced by the cringe-generating sour notes. 

To say it a simpler way: Paul McCartney should quit singing in public.

If his recent performance on the SNL40 program would have been on the old Gong Show, the gong would have been quickly and mercilessly beaten to death!

Paul -- Sit back and bask in the rarified fame-air reserved for ex-Beatles. It's time. I would much rather admire what you were than feel sorry for what you are.