there's a trope out there to that effect. I'm just glad there isn't TOO much when their IS. it has to do with people being overzealous when it comes to "brown is real". the new Galactica was a big offender in this catagory, because girt and grime=hardcore blood, guts, and violence nowadays. a little worn, yes, but not to the point that it looks like the ship's been lived in for a couple centuries straight by the Homeless.
your right about the paint, though. it's even close enough to qualify as cannon. according to one of the books, the original ships were sprayed with a light grey thermacoat. the paint on the A was left off to save several tons of weight (and probably several million credits of pay to dockworkers). people apparently so liked the appearance of the bare alloy, they left it that way (thus why TMP ships have visible Aztecing).