That green skintone some characters have looks hideous even in Firefly. I'm not sure if it was meant for an earlier version of Firefly, or maybe for the P4 renderer, but it doesn't look good with recent versions of Firefly. Some products by very good vendors have it, so I can only assume it used to look good with earlier versions of Poser.

IIRC (it's been a long while since I've used V4) is because the "color" chip in the Poser Surface Node V4 textures is set to some sort of off-white color. If you have the patience to go through each material assignment, just change the diffuse color chip to white. Resave for future use.