You can't gauge the truth of an opinion by the frequency of its repetition. Exhibit A: Builders' opinions concerning energy, insulation, heating, and cooling. A fair percentage of these beliefs ó derived in part from product marketing, obsolete recommendations from "experts," and oft-repeated tales heard at lumberyards ó prove upon examination to be half-truths or outright misconceptions. But like Whac-a-Mole pests, they just keep popping up.