After re-reading this most useful thread from the top, there appears to be no mention of whether Gx bonuses can be gleaned from stays where points have been earned but no stay credit was earned (e.g. free nights, whether from use of points or from NBT/FFN redemption). Presumably the answer is "no", but I don't have first-hand experience to be certain.

An answer from someone who knows would be a nice addition to this compendium.