Very tame version of what could happen. One property in the recent Allsop auction comes to mind. It was in the previous one too and the buyer hadn't viewed it first. Turned out to be so bad that he walked away from his deposit.
Description in the second auction had it listed that the downstairs was currently un-inhabitable. Now while reading that remember that EA's have been known to call shells of old country houses with roofs collapsed as "in need of modernisation" and you get the idea of how bad this place was.