My two just LOVE to "plow" (shoulder to the ground and push with hind legs) through the grass outside. And they frequently don't care (seemingly) just what they plow through !
Could that be happening with yours, or are you talking about not being able to "clear" any scent after bathing ?
I use several type Shampoos (doggy rated) which have some perfume scent, usually buy from PetSmart.
Have a good Day !
S.W.