By the time the Somerville Circle starts filling up on a snowy Tuesday, the lots that were handled properly are already black and wet and open. A-1 Spotless Inc. takes on Bridgewater winters — plowing drives and parking areas, shoveling walks and entryways, spreading salt in the shaded corners where a patch of ice will otherwise sit all day. Snow up the Raritan valley likes to arrive overnight and become somebody's problem at six in the morning, which is precisely what the plow trucks exist for. The standard the name points at is the one the work aims for: pavement, not a rutted layer of packed white. On the far side of a storm the only evidence anyone came is that nobody slipped.