House that had been rented out for a few years prior to going up for sale - needed renovation.
To the point that the floor in one corner (bathroom) felt very odd when you walked on it (you could feel it sag and rebound as you stepped onto a sound part) and you could see visible mold/mildew in one corner (by tub enclosure). It was obvious to ME - apparently my allergies to mold & mildew make me hyper-aware of what the stuff looks like....even after it has been painted over.....
How the real estate agency missed it before starting to show it, I do not know.
It had a very "interesting" layout, as well, originally had no access from the house directly to the back yard. The kitchen let out into the carport, where you had to go around a storage area at the back to get to the back yard.
Someone, at some point, had cut a door in one bedroom into the back yard - but I don't remember there being a closet in that room any more....which meant that it was no longer a bedroom.....and there were other quirks, too - but the spongy/bouncing floor with the mold up one corner by the tiled tub enclosure got to me..............