I think that the fact alot of the women on BB this year have tried to use a 'sex, nakedness, or looks' card, and in the process diminishing their personality, intelligence etc, is a big factor in this!
It's obvious he's found the majority of the female HM's shallow. As Derek himself has said, he likes 'strong' women, something that has been lacking in most this year! He probably has no respect for women who act like that, and the public it seems have taken the same view!