Americans as a whole are conflicted about lobbyists. We don't like to see them buying influence for "special interests" -- unless we personally are one of those interests. We probably put more trust in used car sellers than lobbyists. And, if pressed, we probably acknowledge that the First Amendment gives a Constitutional protection to lobbyists.
From my own experience and from reading the research on the topic, however, I think that the influence of lobbyists on national security issues is greatly exaggerated. Congress willingly funds a large defense establishment in part because of the arguments of military officials at the top and in part because of local interests at the grassroots who want jobs and bases at home. Most of the time lobbyists are just recyclers of those strategic and parochial arguments.
Where lobbying is huge -- and makes a difference -- is on domestic policy. A recent article in The Hill newspaper summarizes the "top 10" lobbying victories this year -- and none of them dealt with a national security issue. Further evidence comes in the fact that, in 2010, the U.S. Chamber of Commerce alone spent almost as much on lobbying ($132 million) as the entire defense industry ($145 million).