refactoring in the shower

Some houses are populated only with teenagers. When one gets in the shower they notice the plug-hole is clogged with horrible gunk: hairs of indeterminate origin, bits of soap, spit, bogies, general fluff (like the stuff that grows in your belly button), congealed shower gel, etc., etc.,. But they don't clean out the plug-hole. After all, they didn't make the mess. When they've finished they're cleaner. But only slightly. And they don't clean the plug-hole. Partly because they then notice there's no towel. They curse the other teenagers as they walk around the house naked, dripping water as they go, looking for anything vaguely absorbant they can commandeer.
After a while the plug-hole gets so gunked up tackling it becomes a truly repulsive task. It actually clogs the plug-hole. The shower fills with water - it starts turning into a bath! But it wasn't designed as a bath. Splashes leak over the lip of the door. Water collects under the shower base where it's not visible. Not at first anyway. After a while the ceiling below the shower starts to discolour in a tell-tale circular pattern. But it goes unnoticed. At first anyway. Soon the ring grows so large it's unmissable. But it's ignored. After all, it's a full-scale call-the-plumber-and-tiler job now.

Some houses contain a mixture of teenagers and adults. When a teenager showers sometimes the plug-hole is gunk free and there's a dry towel but sometimes the plug-hole is gunked up and there's no dry towel. They can't quite understand this. But they never clean the plug-hole and never put up a clean dry towel. When an adult showers sometimes there's a build-up of plug-hole-gunk and no dry towel. They know the previous shower-goer was a teenager. Sometimes there's no plug-hole-gunk and there is a dry towel. They know the previous shower-goer was an adult. When they've finished they clean out any plug-hole-gunk and put up a new dry towel.

Some houses house only responsible adults. Whenever they start to shower they don't notice any gunk around the plug-hole because there never is any. And there's always a fresh clean towel. After they've showered they clear any plug-hole gunk and put up a new dry towel.