The Take That star accused the Spice Girl of trying too hard when she stood in at the Liverpool auditions and he said the singer was hated by the crowd, reported Sun online.
"She's crackers. How you see her on TV is exactly how she is in real life. The crowd really didn't like her. She got booed all day long. She was a bit over-excited," he said.
Barlow, 41, said that bosses had told Halliwell she could get the job full-time if she proved a hit.
"She'd been told she was auditioning for the role and, bless her, I think she tried a bit too hard. I do love her for being her though, we had fun backstage. She's sweet but mad."
