Joan's as good as my lady in the dark

Etymology
From or alongside the use of as a sexually available member of the lower classes found in related expressions such as He is our Ladies Chaplaine, but serves Ione and Joan's as good as this French lady. Ultimately a calque of and  expressions such as         (pâsa gunè toû lúkhnou arthéntos hē autḗ esti) and       , which  considered only accurate as an excuse to escape lecherous and adulterous men but which  considered a description of how all women would indulge themselves so long as witnesses and punishment could be avoided.

Proverb

 * : Sex is enjoyable regardless of the status, physical attractiveness, or social station of one's partner.
 * 1) * 1611,, "Vpon Englishe Prouerbs", Scourge of Folly, §386:
 * &lsquo;Ioan in the darke is as good as my lady:&rsquo; Nay, perhapps better, such ladies there may bee.