Since the problem is over, I would "forget" it. All that can come of complaining further (you already have and got the problem taken care of) would be further dumping :-) If you really want to complain, I would have your business owner complain to the plaza owner and ask them to recind any such agreement with the police department as they are irresponsible in cleaning up the messes their dogs make and it is hurting your business. Then I'd leave it for this time. I think the guy probably got chewed out and couldn't find the **** (kind of like your boss calling you a liar) and was angry and then, when you showed him where the **** was and your sophisticated argument, he snapped. I assume it's a bad day at the office when you get yelled at because your dog takes a dump and you don't know about it and your boss tells you to go clean it up only you can't find it.

My cleaner is next to my vets and there's an island/row of bushes between the parking and the strip mall. The vet clients dogs take dumps there before they go into the vets and the rest of us, going to the other stores, have to pay attention to where we step. The cleaners complained :-) and the vets put a special bag dispenser and trash can, etc. and encourage their clients to clean up after their pets, etc. It doesn't always happen but I can sort of understand the larger picture and, though it is unpleasant, for me as a cat owner and cleaner user to have to pay attention to where I step, it's not that big in my overall scheme of things.

I live in a townhouse and on both side of me are multiple dogs owners and they wander into my yard and take a dump occasionally but it doesn't happen that often and I prefer to battle about (and get help for) other, bigger things so I clean up the dumps.