I always pack two things for my cruise bathroom that I'll thank myself for later
In:I've learned a few tricks over my many years of cruising to make it a better experience, including the cruise ship bathroom.

Every Royal Caribbean stateroom has its own bathroom, and it's likely going to be very small. Unless you book a sprawling suite, standard bathrooms are compact, utilitarian, and offer just what you need during your cruise.
There isn't much air circulation in there, and you can joke about washing your hands and using the toilet at the same time because of how small the space is.
No matter which ship or stateroom type I book, I always bring two things with me that truly improve your cruise ship cabin's bathroom.
I bring air freshener

The small bathroom space is not only tiny, but an area you have to share with others in your cabin.
No one wants foul odors to permeate, and given that everyone is doing their business at least once per day, it's easy for a smell to build up.
For a while, we'd let the bathroom "air out" before using it. Or even relegate someone to the public bathrooms around the ship to avoid it all together.

Then I discovered certain air fresheners really do work well in masking and eliminating the odors completely.
My preferred option is poo-pourri spray because of how effective it is. I never thought it would work as well as it does, but a few sprays and you're good.
It says to pre-spray before you use the bathroom, but I've found it works well enough after too.
I keep one in my toiletries I bring on the cruise, and then stash one on the sink so anyone can quickly utilize it as needed.
Liquid hand soap

Another case of "I didn't know there was a better option until I tried it" is related to soap.
Royal Caribbean provides a bar of hand soap to use in each cabin, but it annoys me when I use it.
It leaves my skin feeling dried out and it gets gummy and takes time work up a lather. Not a big deal, but I usually sigh or roll my eyes before using it.

I've since committed to bringing liquid hand soap with me to keep in the bathroom.
Not only is application easier, but it lessens the hassle of using the bar.
Washing your hands is so important on a cruise ship to reduce the chances of spreading germs, especially related to using the bathroom.

Norovirus is a well-known affliction that can occur on cruise ships. Norovirus is transmitted when someone ingests particles of vomit or feces from an infected person, such as through consuming food touched by an infected individual, touching contaminated surfaces and then their mouth, or placing contaminated objects on clean surfaces.
Because of this, proper handwashing with soap and water is the best way to prevent getting it.
Maximizing your cabin bathroom

While on the topic of a cruise ship bathroom, I think there's a few other tricks for making your bathroom a better space overall.
Unless you're in a suite, expect storage space to be a limited. In fact, there's very limited counter space.
Some cruisers recommend buying an over-the-door shoe organizer to add more storage, but I prefer a hanging toiletry bag as a better and more useful option.
Our own writers really like this option better because it not only leaves the counter less cluttered, but there's less unpacking and re-packing later.

Be sure to also request extra towels from your stateroom attendant on the first day of the cruise.
By default, you'll get a few towels in there, but they will be used up quickly.
Not only will you use towels to dry yourself, but I find the shower leaks a lot when the door or curtain gets opened. No matter how careful you are, water seems to get everywhere and the shower towel provided is miniscule.

Your bathroom can also act as a wash and dry space for your clothes.
Royal Caribbean offers laundry, but it's expensive and some clothes can't be washed in the very hot water they use.
Instead, you could do some basic laundry in your stateroom (no, there is no self-service laundry machines on Royal Caribbean ships).

You'll want to bring single-packet detergent with you, and then fill your sink up with water to wash small loads of laundry.
Wash the clothing in your sink and then hang the clothes to dry in your shower on the laundry line that's in your shower.
While doing laundry on a cruise may not be exactly what you had in mind for a relaxing vacation, getting more use out of clothes is a necessary evil so you can pack less or re-use clothes that are otherwise soiled.