1. Many women, especially during the warmer months, will use water proof makeup. Some of that stuff will last for 18 hours, and like KingMidnight pointed out, it's made of scary substances. It makes the mask-look scarily possible.
2. Why bathe when you can just apply more cosmetics/deodorants?
Neither option is pleasant, but both are plausible.
Don't know much about make-up, but- even though I'm a nerd- I have had some success with women in my life. At a few occasions I have been in a shower, together with a girl who was wearing makeup.
This practical expermiment led me to two conclusions;
1. Besides some space-issues the intimacy of the shower combined with practical aplications of the showerhead makes showering an awesome foreplay.
2. Makeup is based on some pretty nasty fat substances (as the water clearly was rejected from the skin and ran down in clear beads, leaving the make up pretty uneffected)