OK - you didn't say that in your first post. Generally when grunge textures are used, they're used in a style that is quick cuts, jumpy moves, nervous energy, and the chaotic look of what I was talking about would fit it perfectly. Smooth grunge just doesn't bring much of anything to mind. Kind of like "easy-listening heavy metal".
If you take a look at some of Artbeats Film Clutter series, you can see examples of what Kevin is talking about. A great way to experiment with the fractal noise plugin is to apply it, choose several of the parameters, then use Brainstorm button - the thought balloon icon with the light bulb in it. It will give you more quick ideas than an hour's worth of twiddling with settings. Good luck!
Joe Bourke
Owner/Creative Director
Bourke Media
http://www.bourkemedia.com