I don't know if it will do much good, but I complained when I checked out. I remember having a 20 minute argument once with a hotel manager on checkout telling him I didn't make the 1 hour phone call to Honduras from my room. He finally agreed to remove it from my bill, but he acted like I was trying to pull one over on him.

Before I left my room, I left a handwritten note on the back of the "your room is being serviced by" card. It said I hid my coffee filter somewhere in the room for them to find. Of course I didn't actually do that (I wouldn't want some subsequent traveler to get that surprise), but I'm quite sure it resulted in the housekeeper turning my room upside down trying to find it.