One of the worst that I can think of is by Mariah Carey (can't even remember what it was called, but it was awful!). Just goes to show that having a voice is nowhere near enough. Mariah carey 8-octave voice and produced nothing but crap! Joni Mitchell, only a 4-octave range, but look at the brilliant songs that she gave us! Don't get me started on the current bunch of plagiarists! Absolutely awful, the lot of them! Especially the inexplicably successful Sam Smith! 
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