I wondered that, but then (e.g) the famous painting of Elizabeth, Lady Forbes by Sir Joshua Reynolds from the same period sports both lipstick and rouge

Paint & rouge *can* be an indicator, but it was also v. high society French (so fashionable if you could get away with it). Here the plucking of the rosebud & 'temptation' in the title are key clues – pleasure gardens in general & Bagnigge in particular were known for sex workers

Huh. Looks like he did that a lot. This is an example of why I should leave this kind of thing to actual art historians.