Why spiders with long skinny legs?

Spiders can be found throughout your house. No, they do not know where they are in your house or know what a bathroom is, they may just be more visible there as there are usually bugs there due to waste or humidity from showers, and are visible there because there is not much to hide behind. I recommend that you do not kill them. Spiders will kill all sorts of annoying and dangerous bugs that will pester you, so just move it outside of you aren't comfortable with it in your house.

Probably cellar spiders and eating the bugs that favor bathrooms. Probably other spiders about also.
They are not the bad guys, worth having around.
I have a cellar spider under the bathroom sink, been there a few years, a couple generations worth. Often I see an earwig in the web or silverfish. I have another in the kitchen next to the fridge, a jumping spider hangs out by the window, fun watching them catch flies.
My 8 legged natural exterminators and no poisons needed.

It's far better to have daddy long legs in your house tend to have little black spiders with red hourglasses!