"19 year olds" are practically a myth...
Posting such an age is merely a sales-pitch...
Either they're 25+ year old who can still pull off looking like a teen, or they are "that which is not legal" trying to legitimize themselves as 'legal' and could really screw up your life if you were ever busted.
And even if you manage to find that 'freshly legal' unicorn, you'd have to question their professionalism and maturity. Since girls that young are more about 'the scene', than servicing crusty old men, and not connecting the dots that their job usually is servicing crusty old men to being with.....