Uh....you have a total non sequitor here. Can you deny that Liebermann is just about always voting with the insurance companies and for anything that helps Israel?
Can you deny that Ronald Reagan is just about always voting with the private sector and for anything that hurts the Soviet Union? Does this mean that Reagan was in the pocket of businesses and being controlled by opponents of the USSR? Or was he a man with principles, who regularly acted in a manner consistent with them?
Leibermann may be a flaming lefty on social issues (and someone I disagree with almost universally in that arena), but he has been consistent on many issues enough that I tend to believe that his stances are principled (even if he follows principles I do not hold). It even cost him his spot within the Democrat party. You've insinuated something very different...