...all right, it's pretty obvious that Christine couldn't sing her way out of a paper bag, and can't carry a tune in a bucket.
But my question is this: are there, or have there been, any opera singers who are as inept as that? Just wondering. Florence Foster Jenkins doesn't count, because she was never an opera singer to begin with. 
Come to think of it, are there any singers -- period -- who can't sing? All right, I'm sure we can make our own list: Milli Vanilli. MC Hammer. Vanilla Ice. One-hit wonders like Tiffany, Debbie Gibson, Rick Astley, Billy Ray Cyrus. I think we can add Michael Bolton to that list; he doesn't sing, he belts.
Any boy band in at least the last 25 years (since Backstreet Boys). And anyone who ever sang a song on any reality-TV talent show ... except, maybe, Susan Boyle. 
Then there bona-fide musicians, good folks who can sing, but are not part of the artistic role-call because -- *KLAXON!!* -- they did loads of commercials for crap like Pepsi, Diet Coke, McDonald's, Taco Bell, etc. Do they really need the money that bad? Seriously?
All right, Willie Nelson might have. Maybe Michael Jackson, 'cos his dad treated him so badly. But that's another rant... 
Come to think of it, are there any singers -- period -- who can't sing? All right, I'm sure we can make our own list: Milli Vanilli. MC Hammer. Vanilla Ice. One-hit wonders like Tiffany, Debbie Gibson, Rick Astley, Billy Ray Cyrus. I think we can add Michael Bolton to that list; he doesn't sing, he belts.
Then there bona-fide musicians, good folks who can sing, but are not part of the artistic role-call because -- *KLAXON!!* -- they did loads of commercials for crap like Pepsi, Diet Coke, McDonald's, Taco Bell, etc. Do they really need the money that bad? Seriously?