We almost moved due to our next door neighbours.
When we first moved in they were the only neighbours to come to our door with a gift and made us feel welcome but the reality was that they were highly inconsiderate, making noise at all hours.
They were tenants, yet seemed to do constant DIY, quite often banging and drilling from 10pm, even during the week.
They would have loud parties, yelling into microphones until the early hours. I did speak to them a number of times and they'd apologise but carry on.
It made me and DH paranoid to the point where if we saw them getting into their car, we'd check to see whether the way they were dressed made it look like they were out for the day/night; if they came back with shopping, we'd watch them unload to see whether they'd bought barbecue food.
I know that sounds like we're mad but they drove us to it. Honestly, unless you've been in that situation it's hard to describe without making us look like a pair of curtain-twitching nutcases but that's hiw they made us feel and the worst part was the not knowing when the next racket was going to start.
It was a couple and their teenage daughter but oddly enough, they were quite nice people, especially the daughter but they just lived very selfish, inconsiderate lives.
It really affected our mental health in a way I never thought possible, then suddenly last spring, they moved. The house was left empty for 6 months while the landlord updated the property and we were worried sick about who might move in but were so so relieved when a young couple (who have since had a baby) moved in and they are ideal neighbours...what a relief!
Don't underestimate the way bad neighbours can affect you.