Wow, 15 powders mentioned, but only 5 mentioned more than once: Red Dot 4 votes, Universal 2 votes, 2400 2 votes, Bullseye 2 votes, 4895 2 votes, and Unique got 19 !!!
I guess it really is UNIQUE...
Dirty ? Brass from my loads using Unique usually have soot around the mouth and sort of an oily feel. I always figured it was due to the low pressure not obturating the boolits completely, combined with the Lee Liquid Alox fumes. In my shotgun, with no bullet or lube, the only "dirt" I see is unburned powder kernels in the barrel.
I'm surprised that SR 4759 was only mentioned once. It's my standby for rifle cast boolit loads. It gives good loading density and is flexible with regards to the velocities you can load it to. If you look on the burning rate chart in the Lee book, it is right in between H110 and W296, which are supposed to be identical. I recently finally found some data for 4759 in the 44 mag. It works just as well, except for being a stick powder instead of a ball powder like H110 so it doesn't meter as smoothly.