I never found gray water to smell bad, don't know what some of you are dumping down your sinks but maybe that's more of the problem. I carry a 2 gallon collapsible bucket that I use to haul my gray water from the trailer to the fire pit to put the fire out and make sure its good and wet, never had a smell issue.
Sure its not a good idea to dump gray water in an RV park or other established site were other campers are but when dry camping and your closest neighbor is 1/4 mile away whats the big deal. Some of you guys need to think a little instead of just regurgitating internet information.