You can’t get into the pump, so it’s at least impossible to pee in them. I guess you could pee on them, but it would be a pretty high shot, and honestly, why would you?

At the last hotel I stayed at, peeing on them would be somewhat difficult, though not impossible, especially if you have a penis. Peeing in them would be very difficult indeed as you simply cannot open the top easily.

One solution for body soap is basically a handsoap dispenser with body soap in it - you simply aren't peeing in the bag and there aren't many places to pee into.

On top of it all, someone had to show ID to get access to the hotel room, and you are can very well get charged for such things.

In that case, the soap is the least of your problems.

You could almost as easily tamper with a shampoo bottle and leave it make it look unused.

And if the pee on the taps? Bed? Closet? Minibar? Shove the tv control up their ass?