One nasty thing that can happen while you are in the shower is not being able to find where the soaps are located. Personally, it sometimes irritate me that the person who took a bath before me wasn't able to place the soaps in the agreed location.
When you are in a rush while taking your bath because you're already late for work or school, the last thing that you want is the soap missing from the soap dish. That's why you have soap dishes. It's a thing that you are supposed to put the soap on.
It's the little things like this that make living with somebody else a bit difficult at times. Differences in attitudes and living habits, when not discussed immediately, can put a toll on those living under one roof, including couples. How should you go about these little things?
Compromise is always the key. You and the ones you live with should always meet at some point in order to smoothly run things, or one will have to give way for someone else when it comes to mundane things. If nobody wants to make a compromise, nothing beneficial can be taken out of it. It's just better to live separate lives in separate places, then.