I've had a lot of issues with this too. I have a thai ridgeback that can be dog aggressive and has a guard dog type disposition. It's frustrating to me when other people let there tiny little dogs roam on our property so that mine can try to eat them. Grr. I spend so much time saving other people's dogs. I even went to one neighbor and explained the situation to him, but he just told me to shoot at his dog or hit it with a "few good rocks." Another neighbor refused to keep her dog in (this one in a small town), and the mail carrier stopped delivering to my house because he didn't want to pass the dog. I told her he wasn't going to bring her mail anymore either (a lie) and she finally started closing her gate. I can understand why people become upset enough shoot dogs, especially when they kill their animals, but I have a wonderful 30lb mutt that's gotten out twice (in seven years). She was severely abused before I got her and so she is very skittish around strangers. She's never killed animals, but she wouldn't come when called to a stranger. She also doesn't have a collar because she gets them stuck on the fence, but she is microchipped, not that anyone could tell from a distance of course. I guess my point here is that not all dogs that are skittish are habitually let out, I kind of felt like I should say that out of respect for my dog, kind of like I'm sticking up for her, if that makes sense? Probably not, lol.
Paintballs do seem to work. My mom uses them on vultures and foxes when they come after her cats. I also put a collar on a guy's dog once, just for the heck of it when it was roaming, and he stopped letting it out after that. Possibly because he thought someone was trying to keep it. Something weird like painting bullseyes as mentioned, or tyedyeing them with food coloring, would probably get the message home as well. My mom takes all repeatedly roaming cats and dogs and gets them spayed or neutered (which is only $15-30 here). She mainly does this because they kept having puppies/kittens in her yard, but it has the added bonus of encouraging people to keep their pets indoors.
The problem where I live is that there seems to be this cultural norm to impose on all neighbors all the time. Like if someone isn't home people park in front of their driveway, even though there is a space right next to it because "they ain't usin' it." I come home constantly to cars blocking my driveway, or occasionally I get blocked in so I can't leave. Random people on the street just park in the middle of the road as well, right next to a parking space as if it's just too much effort to move over that single car space, lol. Drives me batty.
People do shoot dogs a lot around here, and it's seen as the dogs fault and not the owner's. One lady get's a new dog a couple times a month but she just let's them roam and they are killed or taken to the pound. One of my dogs actually used to be hers.
I'm kind of reclusive and a touch paranoid, so fencing in my 10.5 acres has always been a top priority. I've used horse fence for large areas before, but it rusts. I recently found some livestock fencing that is supposed to last longer that costs about $120 for 300 feet, so that's relatively affordable for me. One day I dream of having some massive, fort-style, log post perimeter ;p I do think it's the other party's responsibility to fence in their own pets, but dealing with people is just far, far too frustrating for me. I get tired of border disputes, neighbor's cutting down my
trees, and so on. I'd rather just have a visible, physical boundary to end the discussion. but that's just me. Other people seem to do better with the whole diplomat/social aspect of this kind of thing.
Anyway, I hope everyone finds a solution that works for them =]