Well your not specific in you mean as far as her entire body or not. I am going to guess you need to take her to the vet and have her anal glands checked. If they need to be expressed it can have a terrible odor. This is easy for the vet to do and not an expensive thing either.
May 21, 2012
Smelly BT by: Linda Galway/TurnerME
Did she roll in something while you weren't looking? It doesn't have to be poop. Could be the remains of a dead rodent, bird, anything like that seems to be a magnet for a dog! Try a different shampoo, too.