Madge seems to have about one or two tracks from almost every album (some have more, some have none) that shouldn't exist, but "Superstar" from 'MDNA' might just take the cake.
Selena Gomez - Lover in Me
Britney Spears - Britney Jean
Demi Lovato - Yes I Am
Janet Jackson - Damita Jo (I cannot stand that album)
Taylor Swift - Red (album)
I just have to remove those tragedies. There's more but they are not relevant enough for anyone to care.