I always make a huge mess when I use a public bathroom
Are you serious? Why do you always make a huge mess when you use a public bathroom?
I'm just relieved that I don't have to clean it up.
You may not have to clean it, but someone else will have to. You shouldn't be making messes anywhere especially in the toilet where your mess could spread disease and induce suffering.
Okay, I'll clean it up if I make a mess.
That's definitely the responsible thing to do. If you make a mess in a public bathroom, or anywhere, you should do your best to clean it, so you don't inconvenience other people.