Q: Is it impolite to put on lipstick and makeup while sitting at a table at a restaurant?
A: In a word, yes. One exception to that hard-and-fast rule is: If you’re with a close friend and you feel the desperate need to apply a quick layer of lip gloss, then at least lower your head so the whole world doesn’t have to watch you make yourself pretty. But anything other than lipstick is really pushing the limit―and degrading the whole experience of going out to a restaurant for the rest of the patrons. I would say this same rule applies when you’re traveling on buses, subways, or trains, although I might be a little more lenient if you’re shielded from the view of fellow passengers. You’re still in a public place, and there’s something unseemly about having to watch someone else tend to personal hygienic business that should be done in the privacy of one’s bathroom. The only other scenario for which I would waive my “No makeup in public” rule is if you’ve just spotted your ex across the room. Then we shift into Ex Etiquette, and you have my blessing to sneak out that lipstick, blush, or whatever else will help arm you for the ensuing encounter. Do what you need to do; go crazy. Otherwise, under normal conditions, please primp at home.