I imagine rain will clean them. In most places it rains every so often.

mywittyname 2 hours ago | parent | next [-]

Rain usually just cakes the dirt. Unless it's a downpour, it doesn't move with enough velocity or volume to remove the dirt. So the dirt just gets damp, maybe moves a few cm with gravity, then dries as a mud cake.

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namdnay 2 hours ago | parent | prev [-]

my experience is that unless you get some really torrential rain, it's not enough to clean the sand/dust/grime

	▲	left-struck an hour ago \| parent [-]
		Can confirm, my car doesn’t get cleaner unless there’s a downpour