There is a tradition in the deep south that may be involved here.
In many cases it has to do with keeping the PVA guy at bay. You look at a place and think it's a junk yard. Old cars as lawn decorations (except there ain't no lawn); siding ten years past due for paint; etc.
Then you get invited in and it's like going through a star gate. The inside is like the Taj Mahal.
What's happened is the outside is kept intentionallly junky, and everything is put into the actual living spaces. And the taxes are kept low.
Of course, some of those places are no more than what you see; eyesores inside and out.
"No Trespassing" signs can be culturally based. In Montana, for instance, they don't put up signs, as such. Instead they use yellow paint and draw three parallel rings around trees, fenceposts, etc.
Hell on strangers who don't know the code!
And who was it that pointed out the landowner's seriousness could be judged by the age of the paint. Three faded rings might mean he was open to discussion. But bright paint, with drip marks still showing, might mean the crosshairs of a .270 were on your temple even as you tried to figure out what the rings meant.