A singing coach who worked with failed X Factor contestant Ceri Rees has accused show bosses of "exploiting" the 54-year-old.
Viewers saw Rees, who has auditioned for the show four times, struggle through an audition on Sunday's show.
The seven-minute section of the programme showed her being rejected by the judges after tuneless performances of I Dreamed A Dream from the musical Les Miserables and I Will Always Love You.
Vocal coach Amanda Roberts told the Sun she tried to persuade producers not to feature Rees.
She said: "The show just wants someone to ridicule. The producers and judges should hang their heads in shame - they are exploiting a vulnerable woman.
"When they approached her to go back I rang the producers and told them it wouldn't be good for her. We had a slanging match for half an hour - they spoke to me like mud."
The clip of Rees, from Bridgend in Wales, was also criticised online by celebrity fans of the show and mental health charities.
ITV presenter Lorraine Kelly tweeted: "Uncomfy to watch ceri on x factor - she's a poor wee soul."
Singer Lily Allen wrote: "they shouldn't have aired that audition, she's clearly ill."
Mark Davies, director of communications at the charity Rethink Mental Illness, said: "While we can't speculate on the state of Ceri's mental health, she does appear vulnerable and it was clear she had been set up to fail."
A spokeswoman for the show said: "The X Factor is open to everybody to apply and we regularly welcome back contestants who want to audition again.
"Ceri has been taking singing lessons since she last appeared on the show and she wanted to have her vocals judged by a new panel as she hadn't been successful with the previous line-up. Her audition was the same length as the other key stories we have featured in the series and Ceri has assured the team today that she is happy she auditioned for the show."
The show employs psychologists during the auditions to help programme makers and asks contestants to "declare any health issues".
TV bosses canned footage of another eccentric performance last year after concerns were raised about east London hopeful Shirlena Johnson's health.