Isn't this just like metal detecting? The irresponsible folks ruin it for the good people? If all detectorists don't leave hole or break laws, then all dog owners don't leave messes. Is anything else any different? Drunk drivers give responsible drinkers a bad name. Obese folks in spandex give Wal-mart shoppers a bad name, etc.
A while back wifey and me went hiking in Falls Creek state Park, Tennessee. At the foot of the falls there was a couple siting with a baby, it was still early so we hung back a ways to let them enjoy and have the falls all to themselves. After a while they got up to leave. But then they noticed the baby needed changing, and when they finished up, we were completely gobsmacked, the girl tosses the dirty pamper into the pool beneath the falls! Went there to take pictures so I had to fish the thing out of the water with a stick and bury it, so it ain't just dog owners...it's stupidity and irresponsibility...in other words..."human nature". I could defend my opinion on human nature but this would become a political post.