On a recent Wednesday night, my wife and I found ourselves in an otherwise empty Beale Street bar surrounded by a group of Australian men. "You guys from here?" they asked cheerily. "You like the area? What do you do for work?" Despite the boozy surroundings, what could have been mistaken for friendly banter was actually research. The Australians were on a real estate tour of American cities, sussing them out before pulling the trigger on the latest trend in this hard-hit sector: snapping up foreclosed homes, renovating them, then renting them out. "America represents an opportunity, and Australians have...