I basically clean the QD part of the can. Take a toothbrush and a solvent and do it upside down so as to not get any in the can itself. I've cleaned it with some water once, and blew air through the can for 15-20 mintues to ensure it was dry, that's about it.
My only basic problem was the crud making the QD feature hard to put on and off, now I clean it regularly.
Basically from what I gather it is not good to shoot while still wet, soapy water might work a little better, but I have not come to a point to where the whole unit was that dirty, just the QD areas.
The unit is supposedly Inconel, so water shouldn't hurt it, just make sure to get it dry.