I experienced the same issue (amongst others) with arterias models...
Indeed, if you have v1, go to mesh / remove / material blends & colors (one of them or both fixed the issue for me). If not, try to import them into a 3d app first, and look for diffuse / ambient values and set them to white. In some rare cases the black was indeed caused by flipped faces that were present in some formats while not in others. Though sometimes the models were all white because the specular value was too high (mostly from fbx imports).
If you deal with 3D content from arteria3d, dexsoft, thegamecreators, then a big help here is (in this particular order): Ultimate unwrap 3d/esenthel editor v1, fragmotion, milkshape3d, various modders converter tools, 3dmax/blender/andotherbig3dsoftware, ... though all you ever need are the first two, fragmotion is a must have if you deal with thegamecreators stuff.
Sadly, as nice as they seem to look in their static renders, arteria's models are hugely un-optimized and often chock full of technical issues like this, but inconsistency is their main theme I believe. ..Missing animations anyone?