I use nitro clean, greased lightning, and an old toothbrush after every couple runs depending on how dirty my rides get. The onroad gets alot of tire dust and road grime mixed with oil all over the place while the buggy is mostly dirt, mud and misc plant material.
I take the engine and electrics out every time and first spray the entire ride down with a degreaser called greased lighning. Then i use the tooth brush to get all the caked on grime loose then finally give the whole ride a final shot with the nitroclean.
I try NOT to use water at all to keep some of the non alum parts from rusting but I'v heard many guys use water with no problems a long as you take care to dry everything with a hair dryer.
From start to finish takes me about 1.5 hours to take apart, clean, and rebuild each ride.