On Max Fisch, there is a website of a OC California Mistress with the scene name of Sensual Latine who gives the best description of slut training. It is quite clear that subs who do fb for Mistresses will eventually be asked/told/made to swallow. Some Mistresses require their stunts to bring medical reports showing that they are std-free. Those reports would not be needed if bare back mouthings were not intended.