I don't have any cats but I constantly have to clean up after my neighbors’ cats that freely roam the neighborhood. I have seen at least 5 cats occasionally in my yard and have no idea whose cats they are, but they all look pretty well taken care of so I don't believe they are strays. The little buggers are using my flowerbeds as a giant litter box, and the smell is really bad in the area around my front step and it is becoming very annoying. I'm so disgusted!
I do believe that my city has a "Cat by-law" in place that states, all cat owners must register their beloved felines and place a tag around a collar. I don't see any of the cats in my neighborhood wearing tags, so there is no way for me to know exactly whose cat is using my yard as a loo.
I don't blame the cats; they are only doing what comes naturally to them. I blame their owners, who obviously have little respect for their fellow neighbors.