I only have experience with 2 powders, Unique and Trailboss, and of the two Unique (the new version) is definitely dirtier. I agree with the observation of others, if you load it closer to max (higher pressures) it seems to burn a little cleaner. I wonder if part of its dirty reputation is due to the fact that so many use Unique for light loads. In my experience, the fouling left by Unique cleans out easily, usually with just a couple of solvent-soaked patches. Not a big deal in my opinion.