Grainy Reflections (A&D material)
If you haven't reviewed the WONDERFUL A&D help document that ships with 3dsmax9, please do so. Zap put a lot of time into that and it's a huge leap forward from the "usual" mental ray documentation that's in 3dsmax.
Along those lines, I've seen a few posts on various forums about noise in the reflections of the A&D material. That noise is primarily controlled by the reflection sample settings, not the FG settings, etc.. here's some examples to illustrate the point.
Basic glossy material with default samples (click to enlarge)
(render time: 1m 08sec)
Increasing the glossy samples will eventually reduce the noise at the cost of a longer render time (click to enlarge)
(render time: 2m 36sec)
Interpolation can be used to balance the smoothness & render times (click to enlarge)
(render time: 1m 34sec)
In short, the A&D material is a super flexible material that I use for practically everything in my scenes these days. So be sure to spend some time with the A&D guide in the help file (F1 button).
Misc. A&D material tests:
Plastics (click to enlarge)
Plastics2 (click to enlarge)
Paints (click to enlarge)