Lessee . . .
Vanilla Ice (He's on "Ice, Ice, Baby" as a DJ somewhere--really!)
Any gangsta-type rapper (Look into the thread for one of the reasons)
Rick Astley (The whole "Rickrolled" thing--the New York Mets damn near had that happen to them)
Celine Dion (My hearing won't go on!)
Any number of "hardcore" metal bands (Screaming words at the top of your lungs is not singing)
As for those who might be on someone's list, but shouldn't (IMO) . . .
Bee Gees--those songs were, and still, hot. Barry's falsetto is entertaining enough for me--and he didn't have to get castrated to be able to sing that high!
Bruce Springsteen--cannot stand his politics, love the music and the songwriting ability. He's had more than a few hits where he wasn't singing the song; he wrote it, and gave it to whomever to record it.
Johnny Cash--if you don't have at least one Cash album, IMO, there's something wrong.
There's others, but I think that you get my drift.