Is it normal to keep the bathroom door closed when not in use?
I have a new roommate from India that moved in a couple of days ago and he keeps closing the bathroom door which confused me a bit at first because I thought someone was in there.
I personally close the bathroom door upon exiting only if I've done something in there which could potentially irritate others nearby.
That is, you close the bathroom door upon exiting only if you're fairly confident that you fucked up and your actions might cause the house to stink up so you trap it in there while the ceiling fan is on.
Otherwise you're just a fucking weirdo.
You're supposed to keep toilet doors closed. Why would you want airborne bacteria to travel around the house? Keep your door closed, buy locks for your door and buy an extractor fan to get rid of nasty smells.
It looks like the Poo-In-Loo is more civilized than you, OP