" ... a sponge has pores or pockets in it. So if I pick up a piece of grit in a pore of the sponge, that grit will stay there, the sponge will act as a carrier and keep that grit pressed against the car."
And the same goes for a mitt. So, you wouldn't use either ... even with a large pail of water and a hose? I see your point ... and it is correct that these can trap grit and them create swirl marks. But, most people use these to wash cars ... and as long as the car regularly sees some wax, it doesn't appear to age the paint much, if at all.
The other night I heard the rain start to fall, so I went out, and lathered up the car only to have the rain stop. I grabbed a gallon jug full of water and a clean plastic squeeze bottle that formerly contained mustard. That's about all it took to rinse the soapy water off the car. The next morning the paint showed fine streaks if you looked closely ... but at a distance it looked like I really spent some time (and dozens of gallons of water) on it.
