Cheryl sings every girls inner demons by taking on self esteem anthems 'Unpretty' and 'Pretty Hurts,' courtesy of TLC and Beyoncé respectively. It's lucky Cheryl is actually the text book definition of pretty because her vocals are all sorts of shocking, and while this wasn't exactly ear torture, the performance was still a no-no.
Some songs you just don't cover, period. Ms Fernandez-Versini is better off replicating her idol's choreography instead.