A house I lived in for 1 year in grade school. The upstairs bathroom had 2 doors, one to the master bedroom and 1 to my brothers' bedroom. To get to that bathroom I had to walk through my brothers' room.
I've seen this at least two times. I have a friend whose parents' house has a bathroom like this; she called it a "Jack & Jill bathroom." The bathroom was only accessible either going through her bedroom or her sister's bedroom. I remember thinking it quite odd. A year or so later, I went to the home of another college classmate (who my friend also knew) and his house (in a different neighborhood across town) also had a bathroom styled the same way -- only accessible either through his bedroom or his dad's bedroom.
House with an attached garage but no door between the house and garage.
Last year when DH and I were house-hunting, we were shown an annoying house like this. It was a nice looking house, but I found it quite odd that the garage was attached to the house, yet the only way to get into the garage was either the big garage door or to go into the house, out the door of a bedroom to the opposite side of the house and around to the backyard back to the other side of the house where there was a regular door to the garage. I said right off it would annoy me to no end to either always have to open the big garage door or make a long journey to get to the back of the house (no door in the back of the house, either) to go into the garage through the regular door.
Also when DH and I were house-hunting, we were shown a house that had a separate building in the backyard that was divided into two rooms that shared a common wall but were each accessible via an outside door. One room had carpet and a wall painted so it looked like it was a playroom. The other room had an electrical panel in the back of the room and a concrete floor with a drain in the middle of the room. It was pretty creepy, and I admitted to maybe having watched too many cop shows because I referred to it as "the killing room." DH later stated he mentioned the room to a friend who said the house was probably used for growing marijuana (and had been seized as it wasn't a regular sale) and the weird room with the drain was likely for that purpose (the backyard also had a weird amount of concrete poured but didn't look like it was supposed to be a patio and had a drain at one end of the concrete slab -- again, the friend said it sounded like a set-up for a grow operation).
The house we ended up buying has one room painted blood-red with a black accent wall (which we refer to as our "Les Miz" room) and one room painted a muted-purple with a brown accent wall. They are very ugly, and we question the taste of the previous owners. There's also a chain-link structure with a roof and a concrete slab that I can only assume is supposed to be a "doghouse" (it had a dog collar hanging from one of the chainlinks). I can't see housing a dog in that thing when even the tiniest chihuahua would not have sufficient room to run around in it. I can't wait to have the money to tear it down. Same with our black "Festivus pole" in the front yard (it is cemented into the ground). We were puzzled over what it was for for the longest time. DH deducted that it was probably the pole for a basketball hoop. I can't wait to get that ugly thing out of our yard also.
ETA: This reminded me --
I once saw a house with 2 bedrooms with a chain and hook lock on the outside. (was visiting) Turns out that they were little kids and the parents didn't want to pay all that money for child gates so they locked their kids in the room.
The "grow house?" The bedrooms, the bathroom and the pantry door all had hook and eye locks up high (so out of the reach of small children). I joked that I guess this was to make sure the kids couldn't feed themselves and to lock them in their bedrooms. Our real estate agent, putting a more "positive" spin on it, said it was probably to keep them from getting into the bedrooms and bathroom, not to keep them from getting out of them (DH was buying the house on his own since this was shortly before we got married so we were really looking at the bottom of the barrel for houses; it made for an "interesting" experience).