I found the avatars to be a bit dark when disabling the head light and using an overhead light. I fixed this by increasing their emissive color
Code:
import viz
viz.go()
viz.move([0, 0, -1])
viz.MainView.getHeadLight().disable()
l = viz.addLight()
l.position(0,1,-.2,0)
avatar = viz.add('vcc_female.cfg', euler=[180,0,0])
avatar.state(1)
avatar.color([1]*3)
avatar.ambient([.6]*3)
avatar.emissive([.2]*3)
avatar.specular(0,0,0)