I've seen the Sexy Socklettes marketed as a sock to wear while waiting for toenail polish to dry and as some sort of half-sock-half-leg-warmer. How often do women paint their toenails? There is no way that it is so frequently that a special pair of socks is needed.
Why would anyone wear these (or any other sock!) with flip flops?
Traditional Japanese attire calls for flip-flop-type platform shoes and white socks, the socks are sort of split (like mittens) with a separate place for the big toe.