I had this problem. Neighbors moved in. We welcomed them with a bottle of wine and a couple of jars of homemade jam. Largely rebuffed/ignored. Not interested in talking to us, accepting Christmas gifts that we gave in the neighborhood, nothing. Every attempt to be a friendly neighbor was rejected. Not even a generic wave when driving away and I saw them working in the yard. (Couldn't help but notice that they had no issues developing openly friendly neighborly relationships with others in the neighborhood but only with families whose skin matched theirs. Whatever.)
Over the next several months/year we saw so many litters of doberman puppies being born next door that we eventually wondered whether they were illegally breeding. Non stop barking for hours every day. Overnight. Incessant. The care for the dogs was poor, especially in the winter.
After several months/a year, we went over with a bottle of wine and a neighborly request to consider that maybe during long periods of loud barking they could put them in the garage or something, as their dog pen was situated directly outside our bedroom window. They didn't have any interest in trying to mitigate the situation in any way. "Dogs bark." (Well duh, we know that -- we were trying to find a mutually agreeable... never mind.) They kept the wine and basically closed the door in our faces. They did blame a lot of the barking on another dog that was being let loose to wander through the neighborhood -- which was also not allowed,
Fair enough.
We repeatedly reported the loose dog until it no longer showed up.
We tried the ultrasonic chirp thing that is triggered by barking. It works a bit, for a while. I do think eventually they develop the ability to tune it out.
We recorded the barking until it went over the noise guidelines not just for the neighborhood, but for the county. At some point it officially becomes a public nuisance.
Marshalls got involved and it got REAL quiet over there. No more new puppies every quarter, either.
It's been a few years since then. Barking is a lot less intrusive now -- dogs eventually got used to the neighborhood, we eliminated a lot of the triggers (wandering dogs), and they got a little attention from LE that helped change some expectations.
I still wave and smile and get grudging responses. I like making it uncomfortable for them to be intentionally rude enough to ignore direct eye contact. I have intentionally made conversation when I see them in the yard. Compliment their landscaping, brag on their son's participation in the marching band, good wishes for every holiday, etc. Heaping coals the best I can in the casual encounters. Saw him working on some landscaping stuff over the course of a couple of weeks and I emailed him to ask if I could come over and help him lift/move stuff.
But mostly we mind our own business.
Also, we're moving next year after 17 years here and 31 years since I moved to Atlanta. I am sure they'll be thrilled.