Which is why K street ("lobbying") needs banning.
Special interests will always find new ways to help their friends on Capitol Hill. Mere laws can't stop it; look at how pathetic campaign finance reform was in practice. In my estimation, the only way to keep specific individuals, groups, businesses, and unions from buying congressmen is to greatly reduce or eliminate the power of congressmen to impact those special interests.
Much of that power to fiddle with specific sectors of the economy seems extra-constitutional to me anyway.