As the other housemates were introduced in pairs by Kildare man and host Brian Dowling, Dettori and Clark had to decide who would go the luxury house, and who to the basement.
They first sent model Paula Hamilton to the basement as being more irritating than actress Tricia Penrose.
Hamilton took it well, but laughed bitterly when she saw conditions in the basement, saying: "Oh my God, charming, delicious, oh, now I feel at home."
Next Dettori and Clark had to decide who was more "fake" out of Neighbours actor Ryan Maloney, who has played Toadfish in the soap since 1995, and ex-EastEnders star Gillian Taylforth, and sent Maloney to the basement.
He said: "I'm up for a challenge, bring it on."
One absentee is comedian Jim Davidson who had been due to appear but failed to feature after being arrested and questioned by detectives over allegations of sexual offences, which he denies.
The series is expected to last three weeks.