a better strategy is to do what i do:
never clean your grill, then it builds up a protective coating of carbon which everyone knows is used to purify stuff.
Plus, all the carbon on your grill is not in the atmosphere, so you're doing your part to prevent Global Warming (TM)!
You might check with Al Gore to see if cooking on your carbonized grill might make you a perpetual source of monetized carbon credits.
I kind of think leaving all that char on the grill does the same as burning the inside of a whiskey barrel. Kind of adds a ‘aged’ hint to the food. Besides, I don’t like cleaning.