1. Sheet vinyl flooring did not adhere to the substrate and was installed after fixtures and base moulding. (hence, it was peeling up everywhere -- which did make it easy to remove)
2. Door hinges were installed upside down.
3. Tile floors were installed over massive amounts of duct tape on the concrete substrate (not sure why the tape was there -- but the tiles didn't bond).
4. Holes cut in the subfloor for plumbing lines were in the wrong spot (not repaired) and covered over with vinyl flooring.
5. I have yet to come across a single window that is level or plumb, including the framing around it.
More to follow as I keep working on this one. Maybe some pics too.