Oh, Ryoko's got a sense of taste alright. We see it whenever she reacts to something horrible she just ate. Besides, she'd need a sense of smell, and smell and taste go hand-in-hand. That, and I don't think Washu would be so evil as to not allow her daughter to genuinely enjoy culinary delights.
As for the pain thing? Not so sure about that. I think it's one of two things: 1) She has the ability to turn her pain receptors off. (I think Ben Hutchins put it best when he said that he wished that the human body had a Master Alarm Acknowledged button.) That, or 2) She just has a ridiculously high pain threshold.
As for why the Tenchi-ken affects her so despite either items 1 or 2? Easy. The discharge from the Tenchi-ken scrambles her systems.
As for the pain thing? Not so sure about that. I think it's one of two things: 1) She has the ability to turn her pain receptors off. (I think Ben Hutchins put it best when he said that he wished that the human body had a Master Alarm Acknowledged button.) That, or 2) She just has a ridiculously high pain threshold.
As for why the Tenchi-ken affects her so despite either items 1 or 2? Easy. The discharge from the Tenchi-ken scrambles her systems.