In Schipol Airport 2 years ago, while waiting for a transfer, I was deadly tired and desperately wanted a shower, as the hot water in the hostel of Belgium didn't work the day I checked out.
I looked for a shower booth and found one in a fancy airline lounge. (Was more than ready to pay for a shower but it was only open for 1st class clients.)
With disappointment, I started walking around, and found a free shower booth on the 3rd floor!! Many backpackers like me were happily taking showers.