I have a dog and I get quite incensed when I see dog waste everywhere - please note this small irresponsible minority who let their dogs cr*p everywhere would hit the roof if they stepped in someone elses... Anyway, this may sound bizarre but what the hell, get some chalk and the next time you see it, chalk around the offending turds and write, CLEAN THIS UP! on the pavement. It may be just enough to shock and embarrass the person... Admittedly people might think you're a bit odd but something needs to be done!