On Grooming:
Q: Is it impolite to apply lipstick during/after dinner at a restaurant at the table?
A: It is fine to apply lipstick if it doesn’t involve gazing into a mirror, making a production out of it, using a lipliner, etc. A quick application that is over almost before it began is fine. Anything more should be taken care of in the ladies room.
From Emily Post’s Etiquette Daily.
