I'm not sure when or why tipping the housekeepers went out of fashion, but chances are, their salary wasn't increased to reflect the change. So think about setting aside a couple of bucks a day for the staff. To be extra cool, leave those dollars out daily, rather than all at the end of your stay, since the same person probably isn't cleaning up after you the whole time.
Using anything but a toilet as your toilet
Did you know that some people do their deuces in the shower? If not, I'm sorry to be the one to let you in on that horrifying human behavior. Shower, bathtub, sheets, curtains (seriously, WHY THE CURTAINS?), if it exists, someone will want to smear their business there. You would never be that person, of course! But someone, somewhere, is. And just guess what kind of tip they leave.