When you're interested in somebody, and you think they might be interested in you, you should point out all your beauty problems and defects right away, rather than take a chance they won't notice them. Maybe, say, you have a permanent beauty problem you can't change, such as too-short legs. Just say it. "My legs, as you've probably noticed, are much too short in proportion to the rest of my body." Why give the other person the satisfaction of discovering it for themselves? Once it's out in the open, at least you know it will never become an issue later on in the relationship, and if it does, you can always say, "Well I told you that in the beginning."
On the other hand, say you have a purely temporary beauty problem—a new pimple, lackluster hair, no-sleep eyes, five extra pounds around the middle. Still, whatever it is, you should point it out. If you don't point it out and say, "My hair is really dull this time of the month, I'm probably getting my friend," or "I put on five pounds eating Russell Stover chocolates over Christmas, but I'm taking it off right away"—if you don't point out these things they might think that your temporary beauty problem is a permanent beauty problem. Why should they think otherwise if you've just met them? Remember, they've never seen you before in their life. So it's up to you to set them straight and get them to use their imagination about what your hair must look like when it's shiny, and what your body must look like when it's not overweight, and what your dress would look like without the grease spot on it. Even explain that you have much better clothes hanging in your closet than the ones you're wearing. If they really do like you for yourself, they'll be willing to use their imagination to think of what you must look like without your temporary beauty problem.
Andy Warhol on beauty