I understand that it's a pain in the ass to wander through dog poop, especially when you have to be lookin up most of the time, I've had the same problem before. I very nicely told the customer that I would be charging an extra £5 for the time it takes to clean my shoes and hoses after the job, now there is not a turd in sight! Try that before you cancel the job, you'd be suprised how the thought of more money gets them off their lazy buts!