I thought it was heavily implied that the Reds capture people of importance and 'turn' them, then allow that person to return to their former position, now fully influenced and controlled by the reds. It is mentioned in Changes that a ton of politicians and business leaders all died/disappeared at the same time the red court died.
I don't remember that.. However just because they appear "human" that doesn't mean that they were anymore.. Again, Bianca is a prime example of that, when stressed by Harry's sunshine hanky, she reverted to her true from, that ugly bat creature. Susan as well, once she transformed into full Red Court Vamp becoming the youngest, when Harry cut her throat she was no longer human.
Of the half turned, once the vampire part of them died, if they were young enough the human survived, but those too old simply died.