Yes. If you look in the hot tub, on the foam you'll see brown, nasty scum like when you boil organ meat. That's the literal feces, sweat and dirt that comes off people who don't shower. And that's only what you CAN see. Most pools will have a shower right there because everyone knows it's proper to showers right before entering the pool. Think about it this way, when you get pool water in your mouth, you don't revel in how refreshing it is, you start to plan your day around when you might start barfing, right?