This one opens so many possibilities. I have the worlds worst neighbors, and I've had a running string of them over the years. In all fairness, the guy 2 doors down is the best neighbor I've ever had.
There is no good answer, short of you going to jail. If the city won't do their job, make their lives miserable. We had such a problem with the guy next door, Elaine S., my building inspector, knew who it was every damned day calling in at 8:30. It got to that point gradually, and it progressed from me and some other neighbors calling monthly to weekly. Then I got mad and just kept insisting she do something.
Someone else apparently got the action going because they finally went after the criminal. He went away to prison in mid summer of 2005. We've been cutting the grass ever since, just so it doesn't look so bad. But this year will be different. They've got it up for sale, so they can cut the grass.
And I've resumed my underground campaign of constructive vandalism. The other day I discovered I still had about 5 or so pounds of fertilizer left over from the past. So I spread it around the For Sale sign out front. Tonight, after dark, I'll water my lawn, and the area around the sign. My logic is that if its going to look bad, it might as well look awful.
I pulled that stunt back in 2003-2005, too. My theory being that if the grass was going to be knee high, it might as well be waist high. The inspector may be willing to let moderately long grass go, but they can't ignore a hayfield. Actually, they can, but they look bad for not doing their job.
I wouldn't suggest anyone else do that kind of thing......
But you should know its an option. Just a few handfuls of good fertilizer, thrown to the winds over your fence, at night, when no one is looking.
Then a little water, again, at night, so it doesn't dry out...
On to a comment about painting the other guys side of the fence....
Long ago, in my grad school years, I had a very good friend. He and his artist wife bought a nice house. But it was an inner city home, built in the 1800s, prior to indoor plumbing. That was retrofitted. One day, doing some demo work to make his wife a studio loft, we were smashing a wall and found a treasure trove. We found a bunch of old stuff behind a the wall, and it even included a handful of old photos. In one you could clearly see the original outhouse. And that solved the mystery of the walkway out into the backyard. From 2 of the photos, we got a real good idea of the way that original was constructed.
So a few weeks later, we were off to the lumberyard for materials. Doug was a good woodworker, if slow (maybe its the secret.) But we constructed a work of art. It was great. All varnished, right down to the obligatory crescent in the door. The only part not workable was there was no hole in the seat. He didn't want some wise guy to use it.
And we placed it in its original position, probably within a couple of inches! Of course we had a party to show it off. Then the jerk neighbors next door complained. The city came out and told him to remove it. Outhouses weren't allowed. Worse, he had a detatched garage, and that made 2 structures not attached, a no-no. And of course we didn't have a building permit. So our outhouse went to a needy old man down in the country. And it was time for revenge.
His neighbors were loud and trashy. They lived in the back yard, weather permitting. Their complaint was they didn't like outhouses, and they sat outside all the time. So in comes Doug's wifey, Anna, to the rescue. One day on her own, in a fit of rage, she went to the paint store and bought supplies.
All by herself she scraped the loose paint off the garage, which sat about 2 feet inside the fence. Then she used primer and put on 2 coats. Then the artist in her came to light. She painted an oversize picture of the outhouse on the side of the garage. The door was open in the painting. And seated inside, on the throne, was an oversized naked black woman. All facing the neighbors patio, about 12 feet away!
Wow was it offensive to them. Big deal. Stir up crap and some of it lands on you. Sure enough, the following day the same rigid building inspector was out for a visit. Yes, the offending outhouse was safe and sound, on an old guys farm. But there was no city ordinance regulating artistic paintings (and free speech.) The neighbor was told there was nothing he, or they could do about it. Vandalism would be prosecuted. And to make matters worse, there were codes against privacy fences in that area. They pretty much screwed themselves.