Strange, big, lumbering machines that roll slowly and feature huge circular brushes. The ones I used to see in my childhood were white affairs about twice as high as a car, so that you couldn't see the driver. The driver sat on the right, as if he were an Englishman, the reason being he could see the side of the road better. The vehicle would fire jets of water into the gutter and spin its wild whirly brushes, leaving the street much cleaner than before.

Because of my fascination with science fiction, it always seemed to me that the street cleaners would be the perfect vehicle for defending the earth from alien invaders, provided of course that the water jets could be turned up to spray those extraterrestrials with ammonia or some other household chemical that would cause their bodies to melt.