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 little estimating suggests they could be rare: half the dating population, figure given sky-high US obesity rates that you need to halve it again just to get girls in appropriate weight brackets, then figure that even in the transformation scenarios the girl is still somewhat cute to begin with suggesting that they're only moving up <50 percentiles, halve it again...)