Thanks, Lamia! Since all participants in the story are dead, I don’t have to worry about them protesting about telling it. Just as long as they don’t decide to haunt me, woo!
When I’m living alone, open all the time. When living with an SO, open all the time. When living with a flatmate, closed for showers and toilet use, maybe closed for other uses, depending. Always closed with guests over.
Never. I live alone & never have guests. Just me and the critters, and it’s always a social gathering when I’m in the bathroom. sigh
Ever tried to calmly take a dump with an 85 lb Gordon Setter rolling on his back at your feet?
Seems like a lot of dopers own cats, myself included. My cat won’t tolerate a closed door so unless there’s company the door stays open. Even then, he can open two of the three bathroom doors so even company has to deal with that.
Always closed, always locked (if possible). The bathrooms in our house are in fairly public places, and I’m a private person anyway.
My cats don’t care, and I’m glad because I don’t like to share a bathroom with a single living thing while I’m doing my business. (I’m fine with public toilets, though, before anyone asks.) It’s just awkward to me for some reason.
I live on the central west coast of the US and the question is an odd one.
I’ve only known 3 people that didn’t close the door while on the loo/toilet/john when I was there to witness it. And I’m 51. 2 people really surprised me, the one that didn’t is my husband.
When it’s just me and the cat and dog. Whatever. But if you come visit me, whoever you are, I’m not squatting for anybody’s casual observance. That’s why people don’t just do it in empty lots or on the side of the highway where people can see you …’
But then, I’m on the west coast US …
Showering - always. One of our smoke alarms is between the bedrooms, which means it’s right outside the bathroom and the steam pisses it off something fierce. One of these days, I’ll either swap it with the basement alarm or install a fan in the bathroom. Until then, the door stays closed.
Using the toilet - it depends. If I’m alone, no. The worst that will happen is that my dogs might want to make sure I didn’t fall in. If I’m not alone, it depends on what I’m doing. If it’s just a quick pee - probably not. Our bathroom is located in a place that means privacy is possible even with the door open, as long as no one wants to go to the bedroom. Hell, if the door is even 1/4 closed, someone could stand right outside the bathroom and not see me sitting on the can.
My boyfriend does close the door when he’s in the bathroom but it’s mostly because it can be difficult to stand and pee when the dogs are checking up on you. 
Aside: I’ve never kept cats myself, but I’ve lived with a few. There was one who would meow loudly at night wen the bedroom doors were closed, so I always made sure there were two closed doors between me and the cat. I can’t say that a cat’s protests affected my actions when I wasn’t trying to sleep.