I think that only works for rather specific cases, like if your robot is contaminated but not physically dirty. Usually people care about the mess of dirt as we

I think that only works for rather specific cases, like if your robot is contaminated but not physically dirty. Usually people care about the mess of dirt as well. Also if the frame is open I suspect it will get grit etc inside. Perhaps a more general way to put this is, think about having this bot in a house with a small child. It would need to clean itself after the kid gets it dirty, and it shouldn't stop working if the kid sticks a Lego brick in some gap. These open framed robots are fine for development purposes, but for general use they don't seem practical.