If buying a house, what would make you want to walk straight back out?

[JMSA]

I mean it lighthearted-ish, as we probably wouldn’t be quite so rude! But what is an absolute dealbreaker for you?
For me it would be the presence of a Saniflo/macerator toilet. Evil things.

House covered in nicotine stains or multiple cats & litter trays in every room. I once went to look at a bungalow to do a council house exchange with, there were cats & unemptied litter trays in every room, the smell hit you as soon as you walked in, the householder had a cigarette welded to her mouth & in the space of the 10 minutes we were inside lit another as soon as the one she was smoking had finished 3 times, dropping the tab end in one of the many litter trays, I couldn't get out fast enough.

Smell of fags
Smell of cannabis
Smell of damp
No window in bathroom
Nightmare neighbours
Neighbours property / garden being used as a dumping ground.
Basketball stand outside neighbours door - thud, thud, thud.
Driveway being blocked by inconsiderate neighbours parking opposite.

Viewed a house where the owner was a widow with 4 pugs. The dog smell was absolutely suffocating the second you stepped in the door. She explained that since her husband had died fifteen years earlier, that she'd had the windows nailed shut for security reasons. To make it worse, she had those automatic air freshener things in every room that seemed timed for every two minutes, so the dog smell + chemical air freshener + stale air circa 15 years had me dry heaving. She was a lovely lady but I couldn't consider the house!

30 feet depth of garden and the main train line to London the other side of the fence.