Rantiquette

I suppose that's the thing about etiquette, nothing is written in stone and most of the topics Emily Post wrote about are difficult to translate into our culture. But she has at least one entry that is universal:

Regard For Others
Consideration for the rights and feelings of others is not merely a rule for behavior in public but the very foundation upon which social life is built.
Rule of etiquette the first—which hundreds of others merely paraphrase or explain or elaborate—is:
Never do anything that is unpleasant to others.