When it comes to popular music hardly anyone can be called a great singer.
Cilla Black is ok on gentle ballads, as almost everyone else is too, but on anything more physically challenging she transforms into 'Killa' Black as her voice turns into an unmelodic screech. Thankfully she still has some material worth listening to, as opposed to the likes of Billie Holiday or Adele whose voices seem mainly designed to inflict pain upon the listener.
Even worse, some of the very best lyricists and songwriters seem to have unpleasant voices which get increasingly unbearable when they're called upon to sing louder.
Elvis Costello
Bob Dylan
Bruce Springsteen
Bono
But then again not again everyone can be a Roy Orbison or a Robert Plant.
With Bob Dylan it's particularly bad on some of his live albums and 1980s work.
As an example you can compare his official release of 1975s Idiot Wind with the unreleased 1974 version.