I have always wondered about a certain smell in my house. Anyone with young boys that use the toilet know what I am talking about. To be perfectly blunt about it, it is the "wet pee" smell that pervades the bathroom
after I have cleaned it. Not to be confused with the "dry pee" smell before the cleaning. Now, I say cleaned, but the smell would indicate that I am not cleaning in the right places if it is still present. No matter where I wipe, it is always there.
The other day I was wandering down the Halloween aisle at the local Walmart. I came upon this.

A black light. Years ago I had heard of a mom of all boys buying one to find out where the pee was still lurking in her bathrooms. For $7 bucks I threw it in the cart.
As soon as I got home, I immediately took the light out of the package, went into the bathroom shut the door and turned off the overhead light.
Horror of horrors is all I can say. Just about everywhere I shined that black light something was glowing back at me. I was shocked. What I thought was a reasonably clean bathroom was not.
After I came out of the den of pee, I jumped on the internet to do some quick research on everything that a black light will reveal. It didn't take long to find out that it will also show soap as well.
So, the mysterious glowing substance streaking down the wall underneath the hand towel and around the sink is probably soap instead of pee. Probably. That was somewhat of a relief.
However, the mysterious glowing substance around the walls of the toilet. Pretty sure that ain't soap. The streaks on the underside/back of the toilet that I have no idea how anything reaches back there. Not soap either. The mysterious speckled glow on the other two walls? I shudder to think which one it is.
It was quite a revelation to the boys as well when I took them in and showed them the glowing room. I don't know why. They are the ones who personally designed it.
The moral of the story? Wipe down every surface in your bathroom. Every one.