it's impossible to tell who is normal in these stories.
for example, the guy can start smoking inside, and it will always smell like smoke.
or, the guy can get his own buzzer.
i've had oversensitive neighbors sit there and bang on pots all night because fireworks or construction noise.
like another comment mentioned, apartments are just built really badly. you can hear anything. which leads to friends of mine complaining about stompers, but to me, they're clearly not stomping. they're just tip-toeing around as quietly as possible. when you get people actually harassing you daily, then you figure out the difference.
if you have to set up a machine or device, then you might be the bad neighbor. this is especially true if they don't set up a machine back at you. that means they're just taking in your harassment and not escalating.
people aren't total idiots. they figure someone is messing with them for their level 15 volume and keep it lower. For anyone with a TV, try putting your volume to 15. Is is unreasonable volume? It's very hard to say who is the psychotic neighbor. I've been on both sides: neighbors that were loud but normal (maybe they had bad hearing, or worked at night), and neighbors that were oversensitive, who were petty and bought machines and devices and sprays to really hurt all of the people who lived around them.
> people aren't total idiots.
You clearly haven't met that many people.
> it's impossible to tell who is normal in these stories
The answer is that everyone thinks they’re the normal one. And everyone generally is normal.
I’ve objectively been a bad neighbor in the past. Early 20s me loved loud music. But late 20s me learned how to be considerate of the music volume.
I’ve also had crazy neighbors. One neighbor of mine complained constantly, immediately after moving in, that the communal laundry area light was left on, and I kept promising to try and do better. Of course, I made plenty of mistakes and often forgot to turn the light off when leaving with a full basket. One day he just took the (low powered LED) bulb away like they were his! Was I the poor neighbor wasting electricity? Was he the psychopath who thought he could forcibly control the entire apartment buildings access to light? It’s all in the story telling.