 You can smell a pool it's too gross to get in. Healthy pools are odorless. That pool smell is the chlorine fighting for its life against urine, bacteria, and even poop. Those red eyes you get after swimming are a reaction to other people's pee. Other signs to look for? Are the walls of the pool slimy instead of smooth? Nope. Can you not make out the bottom of the pool? Absolutely not. And lastly, never get into a pool with multiple babies. Do swim diapers even sound like they work? They don't.