Denton made the frank admission on Monday while spruiking his new television show on commercial radio.
"Maybe she was having a really bad day," he told Brisbane's 97.3 presenters Bianca, Terry and Bob. "It was via satellite, but she was so bad and so unpleasant actually that we never put it [the interview] to air. It wasn't just her, in fairness, it was her manager as well who called our producer the C-word.
"It was just an awful experience and so we thought, we're not putting you to air. Goodbye."
Denton also named his favourite interview, which he said was with English-Australian actress Miriam Margolyes – best known for playing Professor Sprout in the Harry Potter films.
"She was the most fabulous, candid interviewee I ever met," he said.
Andrew Denton's Interview makes its Channel Seven debut on Tuesday at 9pm. His first guests will be Led Zeppelin frontman Robert Plant and Commonwealth Games swimmers Bronte and Cate Campbell.
Denton's previous TV show, the ABC's long-running and highly successful Enough Rope, ended in 2008. Speaking at the media launch in Sydney last week, the TV and radio personality said it was taking him time to get "back to full speed after 10 years".
"We have to earn our stripes again, and earn the trust of our audience and our guests," he said. "I think in this very shouty age, where we have weaponised offence-taking, what will be one of our biggest and most important challenges will be to put people on that screen who we and the viewers potentially strongly disagree with.
"Of course, if things aren't working, we're going to bring a fair bit of renovating and cooking into it around episode three, and by episode four Pete Evans will be hosting."
— with Robert Moran