most dogs will take steps to avoid contact with their own excretment. Wonder if puppy has so gotten use to the smell, that it no longer considers it offensive?

You can spot clean the affected areas with a mild commercial doggy shampoo/water solution (e.g. Hart's Oatmeal shampoo- pleasant smelling). Or you can use something more potent in its ability to cover the smells, and for that matter clean. A good example here would be Nutrogena Tar Shampoo. Since the puppy is stepping in it, either is not going to hurt if used to clean the paws and legs with the puppy's excretment on them.

In general you should avoid full bathing more than a couple times a year, unless a specific skin condition calls for it to be done.

P.S. The Nutrogena tar shampoo is excellent to get deer doo-doo off a dog after it rolls in it. It will remove oils from the skin, so not recommended for problem skin dogs.