I initially thought that she was always thinking how she could play down is behavior on camera so people didn't question why she was staying on the show, but I think she has the same amount of grey matter between the ears as Jesse.
Imagine a conversation with just the two of them.......
Nadia is definitely not the quickest of cats at the best of times. She might look good but she is definately not that bright.
If i thought about people's IQ i'd have them something like
Above Average: Anthony, Simon, Alene
Average: Shazza, Cheryl, Vanessa, Sean, Big Andy
Below Average: Jonesy, Michelle
Forrest Gump: Jesse, Nadia
None of them are rocket surgeons though, to quote Glen Jakovich.