With the first season of the show such a huge success in Australia, stars were reportedly so keen to be part of it, but were turned away for one key reason – they couldn't sing.
Appearing on the 3PM Pick-Up, Jackie O said there are even a number of celebs who have been blacklisted because they were tone-deaf.
When asked about the casting process, Jackie said she didn't know too much about how it worked, but did know that being able to sing is a huge factor in whether a celebrity will end up on the show.
"I think what they do is they cast the net far... they cast the net to everyone, and they just see what comes back," she said.
Jackie added that producers are looking for performers with a "good celebrity profile" but added that if they can't sing, they won't be able to do the show.
"They do want it to be entertaining and enjoyable, but [the contestants] need to have some sort of voice," she said.
And this apparently meant that a lot of major celebrities were told they couldn't compete.
However, the producers were reportedly spoilt for choice this year as many stars came to them and expressed their interest.
"They had a lot of people who they couldn't get last year because it was an unknown show. There are people doing it this year that I never would've thought would do it, and it's just because they love the show and want to do something fun," she added.
So far on the show, tennis star Mark Philippoussis and cricketer Michael Bevan have been unmasked. Ten contestants remain.