Hotel towels, bedding, lamps and pictures are rented. I don't recommend taking those. ;) However, you pay for all the toiletries that are in your rooms, especially the soap that you use when you are there. It will just be thrown in the trash.
I don't use soap on most of my skin. It strips away essential oils and dries it so I only use bar soap on "pertinent areas" also saving on soap and moisturizers!