I Used the garden hose, Until It fried the ESC, now, I blow it out and use alcohol wipes fro the diabetiv section at Wallyworld(200 for $1.14)
But every 2 or 3 races I rebuild so it realy doesnt get much chance to stay dirty long!!

I would say use simple green, its amazing stuff an its eco friendly, the only thing I would say DONT use would be brake clean, I use it on my t-maxx 4910 an sometimes it can mess with the plastics, but makes aluminum parts clean as hell

How about the motor and esc, they have holes in them, how wet can they get?

well the motor can get wet inside just let it dry completely before using it again..personally I just blew mine off and that was it

I used to just rinse mine off with the hose until it rusted the screws and and seized some of the bearings. Now I keep an old toothbrush, some simple green and a can of motor spray handy and clean accordingly.

Just washing it down with water will wash the dirt off and make it look clean but you end up with all the metal parts rusting and bearings going bad and squeeky suspension.If its just dust i only use a compresser but do not blow directly on the bearings,just hinge pins,shock shafts blown fronn the top down,never from underneith or you will blow air and dirt into shocks,i do this after a day at the track and everyother track day i pull all the hinge pins out,inspect them and clean the hinge pin mounts and a-arm holes with a small pipe cleaner,wipe down parts with simple green for a brand new look and dry graphite spray on all the camber links suspension mounts for a better than new and super plush squeekless slash.