Nelly Fertado, especially in "I'm Like A Bird". There's something so whiney about the voice.

Miley
Fergie
Jessie J (When she oversings)
Lil Jon

All the members of One Direction, Iggy Azalea, Nicki Minaj, Bom from 2NE1, Lil Wayne, Justin Bieber, Demi Lovato, Miley Cyrus, Selena Gomez, Katy Perry live and Beyonce (sometimes).

Taylor Swift and Nelly Furtado have got to be the worst.

Lady Gaga.

Miley Cyrus, Lil Wayne and I'm one of those few people that can't stand Justin Timberlake's falsetto.

Also, one of my main gripes about Tegan & Sara is their voices. Neither is appealing to me.

JT

Justin Timerlake, there's something so unpleasant about his voice.
Britney Spears, too nasally sometimes although I do enjoy her voice on her first album.
Kesha's live vocals.
Rita Ora, it's just a bad voice.
Will.I.Am, worst thing to have ever walked this Earth.
Any Disney girl except for Miley.

Katy Perry

katy perry

Selena Gomez and Lana del rey

Oh and I CANNOT stand Lil Wayne

Justin Bieber

Adam Levine. His vocals on Payphone. GAWD


Beyonce, so emotionless and it sounds as if she makes grunting sounds like a pig.

Demi Lovato, I really feel that she is yelling like the whole time during any chorus of hers. Like I don't mind oversinging [Christina Aguilera] but yelling I cannot.

omg how could i forget to mention ABBA?

Britney
Nicki Minaj
Kesha