Tiki Rule #67 Do not leave a mark.

A positive traveling experience is within reach if you practice three key courtesies: treating those you meet and those who serve you with respect, keeping your requests reasonable, and always remembering that as a guest, you should not leave a mark (be it physical litter or a negative impression). With these in mind, a week at your aunt's, an overnight at your friend's or a weekend at a B&B will all run that much smoother.  http://www.emilypost.com/out-and-about

This can also be said about the place you live and our environment.