Katie Waissel, who appeared on the show in 2010, branded Cheryl as "disgusting" in a new interview.
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The 28-year-old said: "She's the only one who's been disgusting to be honest - to make such comments, you're like, 'Wait, who are you?'
"It's annoying - it's not even TV, it's just nasty. Simon Cowell has given her a second chance. She should make the most of it.
"It's a bit of a s**t show, to be honest."
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Katie, who famously had a falling out with Chezzer after causing a stir on X Factor, also insisted that the former Girls Aloud star should not be allowed to sing in the duets round.
She said: "I don't want her to sing through it and I don't think anybody else does.
"She looks beautiful in her calendar but, no, don't sing Cheryl. She can dance. But stop it."
Despite finding fame with the talent show, Katie - who now sings in band Red Velvet - also added that she wished she'd never taken part.
Speaking emotionally, she revealed: "If I could turn back time and not fill out that form, I would give every penny in my bank account to do so.
"I have been tarnished by something I can never get away from. Ever."
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