The lighting is one factor as LaurieA pointed out.  However, the material settings should also be adjusted on other props and objects.  This is all correctable with Scenefixer. 

For example, most surfaces will not reflect diffuse lighting 100%, some of it is absorbed while reflecting something back into the environment.  Of course there are exceptions to the rule.  As a starter, Scenefixer defaults the diffuse_value to 85%.  A reasonable value to use.  However, if you are setting up your scene in a darkened environment, that value should be lower. 

Grayed color chips, for the most part, are cheats to bring down the brightness value of the image map.  Not very acceptable where Poser Pro is concerned.