I've said it umpteen times and this proves my point. Most of the housing stock in New Zealand needs knocking down. It looks like a particularly bad DIY-er has abandoned work half way through a very badly bodged renovation. Normally, I'd say that a mortgage company would never lend against a property in that state, but then again, this is New Zealand....
As a point of (little) interest,
'naked' plasterboard (the grey stuff on the upstairs walls in the photos) absorbs moisture and grease over time, especially when it is left in or above a cooking area for a few weeks. When that happens, it's damn near impossible to get the skim coat to stick.
What's that old adage? Something about buyer beware.......?