FWIW, if you live in the U.S., then you benefit from having such data in great quantity, though I don't think it's sliced-and-diced to near the potential that it has: Lobbyists have to follow registration procedures, and their official interactions and contributions are posted to an official database that can be downloaded as bulk XML: http://www.senate.gov/legislative/lobbyingdisc.htm#lobbyingd... Could they lie? Su…
Do you know what they are required to report? For example, if they have a 'social' dinner with a lobbyist, must that be reported? Are the requirements the same across the Executive Branch? All three branches?