OK, so this isn't actually a Pet peeve, it's more about their owners.
I should add a disclaimer that I don't dislike pets. I always had pets growing up and have been negotiating with the husband to get one for the kids. Just not a dog. I LOVE dogs but we live in the city and I number one hate scooping poop (as you'll see in a minute) and number two I honestly think dogs need to have space to run around and be, well, dogs.
Back to the peeve. As of late (all summer) I have been finding cat poop in my backyard. We do not own a cat and if we did it would do its business in the litter box. Anyway there have been countless times I've been out with a shovel and bag, cleaning up the mess. This is a city lot. Our space is 33ft by 100ft and we have a bungalow and garage on that small space, and the kids don't play in the front yard much because of the busy traffic on our street. So the backyard is their one place to play. Added to that we spent a lot of time and effort finally getting our backyard up to scratch this year. I didn't do that so the neighbour's cat could use it as a litter box.
Of course in HOT weather, if you don't notice it right away, it really gets nasty. And wet weather is actually worse. There is nothing solid to clean up. It's just a nice, watery mound of gag-ness.
Twice this summer I went to the neighbour and politely asked them to keep their cat inside as we were having issues in our backyard. I've run out of repellent and the damn stuff is $13 a bottle. Day before yesterday I went to mow the grass. I thought perhaps I should have a look for any recent "presents". Well I missed one and squish!
That did it. I was cranked. Seriously evil. I marched next door, rang the bell and said through the screen, "You either keep your cat inside or I'm calling animal control." The response I got? "Thank you."
Marched back to yard, cleaned up THREE PILES of it (and we'd had 3 inches of rain which means to get all of it you have to take off the top layer of grass, oh my poor beautiful lawn!).
Guess who was out walking the fence first thing yesterday morning? You got it. The cat. What bothers me is that they obviously don't care about their pet. It's against the law here to let your cat run at large. That should be enough. When someone threatens to call animal control, it should be more than enough. Not only that, wouldn't you make an effort NOT to piss your neighbour off? You may want something from them someday. But nope, don't care.
What this whole long irritating post boils down to is that the one thing that really, really annoys me are people devoid of common courtesy. If my animal did that to someone's yard I'd be appalled. I'd be back there cleaning it up and promising it wouldn't happen again. That's the way I was brought up. Responsible. I just don't get it!