Once I remove them from the Emptor, I turn them inside out and use a Kirby Zippbrush to get the embedded dust, dirt, and detritus from the bag.  I then use the crevice tool to get the dirt in the seams' crevices.

Next, for a bag that was not too dirty, I will use a Kirby as a portable shampooer to shampoo the inside of the bag with Kirby Carpet Shampoo.  Depending on the soil level, you can use a clean white cloth or clean, relatively soft-bristle brush to work the suds into the bag.  I then let it hang dry and once dry, I use a Zippbrush again to remove the trapped dirt and dried suds from the bag.  Comes out bright and smells great!

If the bag is really dirty or splotchy, or if it's a refurbishment, I will use warm water in a bucket with Woolite.  I hand agitate and gently scrub the bag against itself to remove built up gunk.  I dump the dirty water and refill with warm water, and hand agitate and scrub again to rinse the detergent out.  I then let it air dry.

I hope this helps!