I can't quite understand it either. People seem to have based their opinion of her on a couple of bitching sessions (when in actual fact, as stated by the BB psychologists, she has been one of the least bitchy of the housemates), and saying that she didn't want to nominate Paul again, but found herself with no other option (i.e. no one else deserved nomination any where near as much as Paul).
I bet none of the people slighting Elizabeth could live in close quarters with Helen for eight weeks and not eventually tell her to shut the **** up. She had to let of steam somehow and bitching to Dean was the best option.
However I can understand people calling her boring, or a bit snooty or picky, but two faced, backstabbing and plotting are so wide of the mark it's untrue.