The Talmud in multiple places (Megillah 13a, Shabbos 80b, Pesachim 43a, Moed Katan 9b, Menachos 86a) teaches that myrrh is either balsam, or olive oil that had not reached a third of its ripeness. Although it smelled bitter like vinegar either way, it was used to remove unwanted hair and to make the skin glowing and smooth. Like sanding a car before painting it, these women used myrrh to prepare their bodies for the beautification process. The verse’s stressing the usage of myrrh (for six straight months!) gives us a better picture of the lengths to which these beauty contestants were subjected in order to please the king.