If that's the case, there should be a large number of undervalued-but-hot girls out there. Such a market inefficiency is just begging for some arbitrage. Either guys are failing to pick up on such opportunities, or are not motivated to go after them. Either way, some enterprising LW gentlemen should be getting into the LBO business!
Obviously there are some, but I don't know whether there should be large numbers. I mean, most girls are well-aware that things like cosmetics and hair-styling exist.
The missing could be no arbitrage at all, in that effort spent finding them, convincing them to improve, and then maybe reaping the benefits (either because the improvement doesn't work or because the girl trades on up - similar to why employers may be disinclined to invest in employees' education) could exceed just improving yourself or spending more time going after existing hot girls.
(A lit...
http://theviewfromhell.blogspot.com/2012/09/toward-non-stupid-non-blank-slatey.html
The author gives a shout out to Less Wrong as a community with a perpetually skewed gender ratio, which is precisely the conditions under which polyandry appears to thrive.
Discuss. :)