I think there's one exception, and that's the (very common) case where the arguer is leaving their point open to implication and then refuses to explicitly make

I think there's one exception, and that's the (very common) case where the arguer is leaving their point open to implication and then refuses to explicitly make it. The wink wink nudge nudgers. Then if you try to pin them down, they keep weaseling out of it while continuing to almost make their argument. After a point you just stop engaging them.