...I've often quoted conservatives when their words support my position, or when they can be used to attack my conservative opponent's position.

But I make no effort to hide the fact I've quoted a conservative writer for my own ironic purpose. In fact, I make it a point to emphasize it. Its a common rhetorical trick to say, "See, even your guy thinks you're full of it".

If I quote Buckley, or Reagan, or Krauthammer, I want conservatives to know I'm quoting one of their own. They will simply dismiss anything I quote from one of my crowd as irrelevant.

As for your slippery slope comment, I must admit you're right on. It is so sad, so sad. It's what happens when mere differences of opinion are presented as differences of moral authority or intellectual integrity. Maybe I'm not the one to make the claim, but I would like to think I'm not the kind to do that.