Christopher Austad, a former fashion model who now sells real estate, puts his photo on mailings, business cards and listings sheets. "People judge a book by its cover. We're all guilty of it," says Mr. Austad of Douglas Elliman in New York City.

He's right. When selling real estate, beauty pays off, says Sean Salter, associate professor of finance at Middle Tennessee State University and co-author of a study on how an agent's looks affect property sales. Attractive real-estate agents list homes for $20,275 more...