5. Towels
I know what you’re thinking: ”So, now basically nothing can be in my bathroom anymore?”. We kind of feel the same way after learning about this. And, yes, towels too. Once again, when humidity strikes, your towels will be affected by damp air and they will get gross.
Storing them underneath the sink is also a bad idea because they are exposed to loads of bacteria and dust. You can place them on a hook but no longer than a week.