For fans of hard-core painting, the summer belonged to Rackstraw Downes, whose series of three exhibitions -- at the Parrish Art Museum, at the Aldrich Contemporary Art Museum and at Betty Cuningham Gallery -- proved that he’s maintained his obdurate position as a reporter of the specific. It can be tough, indeed. Where’s the fun in overpasses, deserts, landfills, oil tanks, off-ramps, ventilation towers and irrigation ditches? But Downes is ruthless when it comes to making us reconsider our nondescript surroundings.