Online shoppers see photos and even take 360-degree “virtual tours.” They use online mortgage calculators and maps to check that a house is close to trains, highways and schools. They compare SAT scores, average home prices and family incomes in different cities. On Rubloff Residential Properties’ Web site, www.rubloff.com, the Blairs even learned the history of their home. It was originally owned by a jeweler who installed secret safes. Sellers benefit, too. They can “show” their homes to thousands of electronic visitors without making their beds. But buyer beware: through clever use of photography, sellers can accentuate a house’s virtues and minimize its flaws. “You can’t tell that there’s a vacant lot with broken-down cars next door, with a pit bull,” says Lisa Hutchins, a Los Angeles broker for Coldwell Banker. “They didn’t pan up to the ceiling that’s falling in from the leaking roof.” The Blairs lucked out: their roof is leak-free, and their house looks lovely.