The Washington Post has a huge exposé on 33 members of Congress who directed earmarks to projects close to their homes, but it's hard to see how this latest "scandal" should surprise or outrage anyone.
The earmarks laid out in the story were not directed specifically to projects or properties that were owned by members of Congress, but were for thinks like roads and parking garages that may have indirectly benefited the interests of the member who proposed them. Senator Richard Shelby of Alabama helped the revitalization of Tuscaloosa neighborhood that happened to surrounded one of his businesses. Others had an impact that were less direct. For example, if you repave a road and someone owns a house on or near that road, the value of their property might increase slightly.
However, if you take that train of thought far enough, any project that goes to a Congressperson's district or state could benefit them financially. If a factory brings jobs, that makes the town a better place to live, which brings more people, which increases taxes and property values, and improves the economy for everyone. Even if they have zero financial benefit to the Congressperson, it might help them get re-elected. Which has its own benefits. That's whole idea behind earmarks.