First, like Ingsoc, conservatism has a hierarchical structure. Like Orwell’s “Inner Party,” those at the top of the movement have almost perfect freedom to decide what opinions count as official conservatism. The Iraq War furnishes a telling example. In the run-up to the invasion, leading conservatives announced that conservatism now meant spreading global democratic revolution.
This is no phenomenon isolated to "conservatism". I recall reading an editorial once saying that Clarence Thomas wasn't really Black because of his political views.
Litmus tests for determining membership are okay as long as they reflect fundamental principles (or facts). For example, the litmus test for Clarence Thomas isn't politics or philosophy, but heritage.
So here the question is whether the war in Iraq (or at least the principles behind it) is a fundamental conservative tenet? Of course it isn't. (Some would argue it is diametrically opposed to conservative principles.)
I think the problem lies when a group confuses its identity with a larger (or different) group. (Republicans confusing themselves for conservatives, for instance.) Another example: I have heard of lay "Catholic" groups or communities whose leadership confuses themselves with the hierarchy of the Church-being over-zealous judges of orthodoxy in their own little fiefdom over dress, educational materials, customs, etc. When leaders over-step the boundaries of their authority, confusion and splintering occurs.
Original sin and its consequences abound.
Oremus pro invicem!