Like @Emilia42, for me there is a difference between being a bit messy and being disrespectful. I charge a significant cleaning fee, so I don’t expect the place to be left in perfect condition. However, I do have the following in my House Rules:
“Please relax and enjoy the unit, free from the responsibilities of heavy household chores during your stay. However, please respect that the unit is the owner’s home, and minimal cleanup such as disposing of trash and left-over food, wiping up spills, etc. is greatly appreciated.”
Also, as part of the check-out instructions, I ask that the guests remove all of their trash from the unit and wash their dishes, as bugs can be a problem in tropical climates. I also ask them to close and lock windows, doors, turn off lights, etc. (This seems obvious, but it’s amazing how some guests apparently don’t think it is!)
These rules seem to be adequate, but even if they are breached a little, I don’t feel that if I have to wipe up crumbs or coffee spatter on the counter, it means that I had a bad guest worthy of reproach.