candidus_cogitens
Explorer
If you want my off-the-cuff opinion, I'd say Sense Motive and Bluff would not be allowed while raging. It takes a full minute, at least, to use Sense Motive for most purposes. However, if all you want to do is discern a feint, I'd say it should be allowed to use it, though perhaps with a penalty. (It would be unbalancing to not even allow a chance to detect a feint, although it makes sense that it would be easier to feint against a raging barbarian.) For Bluff, I'd say feinting would not be allowed, by analogy with Expertise.