Common sense, like, whatever your skin can tolerate.
For the most part, there is no need, per se.
But
A gentle warm water rinse, some liquid dish soap, soft toothbrush, rinse, dry.
I do this often after heavy rain and spattered soil.
Also, when stock gets too grotty. Sometimes it looks right, others, not so much.
Generally, i like clean. Less grit to wear on parts, if applicable. ( real weathering doesnt look as nice, to me, as painted subtle weathering). Less debris in boxes, storage, etc.
Rarely remove axels, but do scrub off old lube, dry, and relube.
Dishwasher....never tried because...tiny stones hard bits, etc, might not be helpful to the washers internal food grinder, pumps, and, once upon a time, the phosphate level in soaps, along with bromine, chlorine, etc., were/are pretty harsh, and could bleach plastic slightly, or remove paint, stickers, plating etc.
I know leaving a tablet of dishwasher soap overnight will bleach out my le creuset stuff a touch....