Have you ever looked in the mirror and noticed you had something in your teeth and wondered: "how long has that been there" and "why didn't anyone tell me"?

After recently walking around my office for a good hour with pepper stuck on my front tooth, my horror was only worsened when I realized how many people I had already exchanged greetings with. Not one of my coworkers told me it was there. I just happened to notice after going to the bathroom and looking in the mirror while washing my hands. It is a possibility no one noticed, but that didn't ease my dread.

What is the social convention for letting people know something is a little off with their appearance? A lot of people don't want to come across as impolite or judgmental and I totally get that, but isn't letting a person (especially a friend, family member or coworker) walk around with toilet paper stuck to the bottom of their shoe or a boogie hanging out of their nose equally rude?

So the question is: