Sounds like a house one of my friends bought. He found out while he was still in the buying process (I've no idea why he went through with the purchase and didn't at least demand a reduction in the cost) that there had been two un-permitted additions put on the house. The first addition is technically sitting on a foundation, if you count the fact that they tied into the foundation under the original section of the house by like, a foot. The second addition they didn't even bother, and that section of the house is just being held up by a hydraulic jack sitting on a brick. Consequently, he has giant mushrooms growing up through a crack near a door at the far end of the second addition, where the entire house has cracked and settled. People do really stupid shit with houses from time to time. Sometimes it makes me shudder thinking of buying a house someone else has lived in, because I have no idea what's waiting for me and not all inspectors can be trusted worth a damn.
Hell, the house my parents are living in now, they discovered after they bought it (and had it inspected by an independent inspector who was either a retired referee or one of the three stooges), that the master bathroom shower was sitting on bare plywood instead of cement board like it was supposed to, so the floorboards were rotting out. When my dad started pulling away some of the ceiling from the room beneath it so he could check the damage, he saw that the floor joists were 8 inches further apart than they were supposed to be, so he had to add more joists to the floor, but because of various structural oddities he had to take a sledge hammer and drive the joists horizontally through the floor/ceiling of the second story of the house for about 8 feet to ensure that they'd tie in to both of the load bearing walls that were holding up that portion of the second floor.
That summer he decided to tear out this retaining wall that had been made of old railroad ties because it was doing a horrible job of actually retaining that portion of the fill dirt by the house. We dug out a bunch of the fill dirt to take pressure off the wall, pulled the railroad ties and rebar out, and dug down a little further so we could put in the gravel filler and tamp everything down before we started stacking the keystone blocks in, and discovered when we got up next to the garage that the garage wasn't tied into a foundation at all - the building of the garage was just sitting on top of the concrete slab. I have never heard my father swear so angrily as he did when I showed him. To make matters worse, a couple years later they started having really bad mouse problems in the kitchen. They couldn't figure out where the mice were coming in, so my dad started investigating some of the walls, but hadn't really figured it out yet when the front wall of the house fell off. It literally pulled away from the rest of the house and fell off, windows and all. Come to find out the entirety of the house had been sitting on top of the foundation, but hadn't been tied to the foundation in any way, and as the hill behind the house crept ever downward, it had pushed the house 6 inches forward and the front wall was no longer sitting on the foundation.
It's taken them eight years and they've finally finished repairing everything that the contractor who built the house back in the late 70s fucked up, but when they tried to get insurance and/or their warranty people to help cover it they were turned down because "the house was built before building codes had been established for that county."
But still, having all of the plumbing tied into itself like that sounds like the landlord or one of his buddies probably did it himself/themselves because that's fucked up.