At most all hotels (

) we tip $1 per day per person. If we've been messy, eating in the room, etc, I add a couple dollars to that.
It's a personal choice to tip or not. This is just my personal opinion: Housekeeping is there to take care of the room, if
I have made a mess (crumbs on the floor, extra trash, etc) I want to show my appreciation to someone who will be cleaning up after me.