Corollary: this means that certain types of low-contrast skunge can build up to a rather alarming degree in the shower area, because they're invisible when you're actually taking a shower, and when you can see them, you're never in a position to be looking at them.
This is especially true if the skunge just looks like hard water deposits when it's all dried out, but absorbs water and turns into, like, transparent goo when it's wet.
Invisible, that is, until someone decides to wear their contacts in the shower one day, say so they can shave or something.
Ew.
