The Bathroom Door.

I find it very irritating when visitors arrive at my house. Aside from the fact that I am not very fond of actual people, I think that it may be because visitors shut the bathroom door.
I am very bothered by this. Not that they shut the door during the act of utilizing the facility, that is clearly expected, but that they shut the door afterwards. I see no reason for this. It only causes confusion for those who wish to enter the bathroom at a later time. You linger around the bathroom door thinking that someone must be inside and you don't want to knock, but after 20 minutes you can only assume that person must be doing some serious business in the bathroom of your own home. After debating and quarrelling over it with yourself you finally decide that knocking may be necessary, and when nobody answers you think, "maybe they are too embarrassed to admit that they have, in fact, been in the bathroom for 20 whole minutes, and they would then be clearly admitting to taking a massive 20-minute-long-poopie in my bathroom."
With this, I ask you, please do not shut the door after exiting the bathroom. I do realize that sometimes this may be a step in preventing the smell from seeping into the rest of the house, however, smelling poopie is quite obviously less agonizing than the aforementioned guessing game.