How come her looks never regressed?
Elisa Cuthbert is beautiful, so I can't complain too much. Still, it's clearly unreasonable that her appearance never regressed. She endured four days of captivity, yet her hair, skin, and complexion remained perfect.
She had no shower and other tools for grooming, and even if you presume she did (off-screen), then you can't expect that she would overlook the trauma to brush her hair and such.
It would have been sharp to see her hair start matting as the movie progressed, for example.