Most people want to know about any appearance faux pas and would prefer to hear about it in privately and with care.
Someone once told me that if it is something that can easily be fixed, like the zipper, toilet paper on a shoe or tucked in the back of trousers, ink on face…let them know. If it is something that cannot be readily fixed and really is not of importance, let it go. A couple of co-workers admitted that they’ve worn one black shoe and one blue shoe to work. Once someone pointed it out to them, they were embarrassed for the rest of the day.