I'm currently doing an unmodded dungeon run (see the GRPD Random post in General) and encountered the room pictured below. Notice that my inventory says press shift for quick sell mode (but I can't actually sell here).
I've had this happen once, but I'm thinking the devs fixed this all with the latest patches, since I've never seen it again.
I've had similar (yet different) experiences, but they were before CoTW. One of them involved a zoo with no monsters. It showed up as a zoo on the minimap, but no monsters were inside and the monster counter didn't show up. Another changed Brax in to some sort of Brax-Dredmor hybrid. Brax had the same sprite and description as Dredmor, but his name remained as Brax. Killing him caused you to win the game. Either way, I haven't seen this. I haven't updated to the latest patch, though, 'cause Steam Cloud will nuke my saves if I patch.
Did you try to steal anything? Oh, wait, no goods either. Too bad! I wonder what would have happened if you started stealing like crazy, heh.
I had the exact same thing happen with the exact same layout. It didn't cause any other problems so as bugs go it was no big deal.
Don't hold me to this, but wasn't the first room posted in this thread (1) Added by Fax in YHTNTEP as part of the old Interior Dredmorating, and (2) Intentional?
I've recently gotten this error too, on the same floor and shop design as the OP. Here are my save file and a screenshot (well, technically a copy of the thumbnail from the save file).