Think tanks are better than lobbyists, because they let interests launder their money. X, who has an interest in Y, can make a donation to e.g. Heritage, which

Think tanks are better than lobbyists, because they let interests launder their money. X, who has an interest in Y, can make a donation to e.g. Heritage, which will then spit out PR in support of Y. But that usually comes across as "Heritage supports Y" and "X donates to Heritage," not a single fact that "X supports Y." And since Heritage flacks for hundreds of Ys, X has plausible deniability. And if you want to see the amazing ROI available through corruption, take a look at Duke Cunningham's bribe menu.