I used to have a little Maltese that loved to roll in dead things. Since we had cats there would sometimes be a dead carcus in the back yard when she went out and she would find it first thing.

Even a worm or other odd thing that she could find she would roll in.

It was especially disconcerting when she would do this directly after her bath and grooming. I don't know why they like to be stinky. Have you ever noticed how they like to roll around on the floor and furniture right after a bath? It's like they don't like smelling clean!