I'm surprised at RJ's response when cats peeing and crapping in your yard is infinitely worse than a dog doing so. Cat pee is so gross, we used to have a neighbours cat come over and pee and spray all over our driveway. it was so offensive and that smell never goes away!
Personally I try and get my dogs to go on the nature strip, rather than a persons property. Generally speaking though they always wait to get to the park before they crap. Obviously people who don't pick up after their dogs are bastids. Although I am sometimes really surprised at people who admit to not doing it
Who wants **** all over the place to potentially step in and then traipse through your house unaware and then having to scrub your shoes and mop your floors
?