J BI do agree with you up to a point. When you state "Lobbyists lobby across political lines in whichever way best suits the special interest group that pays them" I think you infer (correct me if I misunderstood you) that the group which financially supports the think tank is homogeneous. This is sometimes true. However, some think tanks are respected for the work they do. They do lobby, of course, but they do not necessarily align with the views of their supporters because 1. Sometimes the funding is not the the think tank itself but to a particular project instead; and 2. Sometimes there are just too many people and organizations who fund the think tank.This was in fact something I did check out before starting the post and I was satisfied with what I saw. If you are interested, do check out WRI donors list (http://www.wri.org/partners/contrib_financial.cfm)I do believe that sometimes to be independent from special interest groups can be a very worthy asset for a think tank (easier said than done, of course)