Basically, like crap with age being evident and messes littered across the room. Most of the waste had decayed to the point of not being too much of a problem, although there are bones here and there. Artholath is using the mindset of a long time ago, so the mess he refers to is bones and dark spots at this point. The whole thing is a bit rickety, being underground and located under a castle with some occupants in it (that nobody knows is there on either side). The exit is long blocked off, although going a little ways in would allow for some punching through to the other side of a tunnel made not too long ago that was cancelled for whatever reason.