Doggie Doo-Doo

Yesterday evening after dark, returning from the supermarket, Marash GIrl was carrying groceries from the trunk of her car to her porch, taking a short-cut by walking over her front lawn (as opposed to walking along the sidewalk and up the stairs).  Soon enough, she had carried all of the groceries from the porch, down the front hall, through the dining room into the kitchen.  But the strangest of smells followed her, and when she looked, sure enough, there was doggie doo-doo all over the bottom of her brand new right running shoe.  

Any suggestions as to how to encourage the folks who walk their dogs to pick up after their dogs?  Cleaning up her shoe and her floors last night was not fun. 

N.B. Newton (Massachusetts) has a leash law, so there are no dogs running loose . . . only dogs on leash being walked by their owners. . . unless the leavings were from a well-fed coyote from Cabot Woods!