Spiders just hang out in the shower. Are there more flies in the shower than the kitchen? Unlikely.
I think that the obvious conclusion is that spiders like to watch you bathe.
There you are all naked and wet, blinded by shampoo, and out of the corner of your eye you’ll catch that creepy crawly movement. So you search about you, but all you have is a million puffy sponges and a shampoo bottle. So you beat the spider to death with your shampoo. And then you're stuck. You can’t set the bottle back down without getting spider guts all over and there’s absolutely no way you’re washing it off in the shower and getting spider juice all over in the water swirling around your toes.