OK, I'm still on a learning curve with Materials.
I'm wondering how I can utilize the AM noise Materials to act like a Diffuse Decal? Let's say I make a Material, set it to fBm, and set one color to white the other to black. Now if I apply this to a model as is, it acts like a Color decal (and I know I can make it act like Bump and Displacement maps, and even use it to control Spec Size and Intensity). But I can't seem to see how to make it act like the Diffuse Decal type which just lightens or darkens the underlying color or decal.
I like to use Diffuse maps to lightly break up the color of a model, like a layer of dust on an object, and it would be really cool if I could just use a Noise Material and drag it onto the whole object for this purpose.