Blimey, where do I start?
Our house is a 1930s bungalow which was massively extended in the 1980s by the previous owner, who apparently was a builder. I pity anyone who ever paid for his services. We started out with:
Insane wiring, upstairs shower on downstairs lighting circuit, outside light cable just drilled through a hole in the living room wall and plugged into a regular socket. Fountain 50 feet up the garden powered by cable nailed to fence and similarly drilled through dining room wall.
All sockets randomly in the middle of every wall. I mean four feet from the skirting.
Nothing boxed/chased in, so pipes running everywhere.
Massive picture windows but no lintels above them, so roof/upper storey supported by a couple of rows of dangerously sagging brickwork.
No floor joists in loft conversion; floorboards just laid on ceiling joists, so massively sloping.
Soffit and fascias made of cheap particleboard, gloss painted.
Tiles on tiles on tiles in both kitchen and bathroom. Rather than remove random unused switches and sockets they just tiled around them. Never bothered to grout the tiles in the kitchen, but filled massive gaps around the edges with massive swirls of dark brown sealant.
Swirly Artex on every ceiling in a failed attempt to disguise the edges of the poorly installed plasterboards. The living room ceiling was gloss-painted for good measure, like a giant upside down meringue.
We have pretty much spent the last six years working though all this.... nearly there!