The reason why women used to wear leg makeup in the 40's was because during the war, nylon stockings were very scarce and expensive. All materials were supposed to go to the war effort to help the soldiers. So regular women would put black powder on their legs and use eyeliner to draw a seam up the back of their leg. Just a little nugget of fashion history :)
Oh dear, looks like we forgot to do our homework on that one… Thanks for that fashion history fact!