My new weapon

Several years ago, on a whim I bought a UV black flashlight from Walmart.  I went home, shined the light in my bathrooms and was horrified at what I saw.  I learned a valuable lesson about cleaning a bathroom.  You have to wipe down everything and I mean everything if you don't want scary things shinning back at you with this light.

After a year or so, that light broke and I never replaced it.  The boys clean their own bathrooms and with the purchase of a new one recently,  I decided to see how they were doing.  Particularly on the dark brown - never shows anything - tile.  

I went down into their bathroom, closed the door and turned on the light.  Would you be surprised when I told you I was surrounded by glowing drips and puddles?  Neither was I.  Not a bit.  When I took them in and showed them, they all immediately blamed each other.  "I didn't do that.  It was so & so"  Yea, not surprised at this reaction either.   So now I have a new weapon. They tell me they have cleaned and when necessary,  I can verify.