I agree with him, I don't like dogs but have to walk my mum's daily, I don't have any affinity with other dog owners who I meet so have no problem telling them to clear up their mutt's crap. IMO the majority watch their dogs in "business" and only clean up if somebody is around, or like me, waiting for them to act.
The woods where I walk have many trees liberally sprinkled with little bags of poo, lovely, the excuse of "We leave them there to pick up on the way back" being, well, poo.
The dog walking businesses are the worst, really, you think they clear up after 5/6/7+ dogs?