Photo courtesy Sheltering ArmsPeople are sometimes suspicious when one of Scott Pool's inspectors calls. The offer -- to weatherize one's house for free -- sounds too good to be true. "We have to convince them that, really and truly, nobody's going to charge them," says Pool, the weatherization director at Sheltering Arms Senior Services, a multi-faceted non-profit in Houston. "People have to be assured that there's no scam involved." Weatherization means caulking, insulating or otherw