Journeying to Tear to get Callandor, Rand is pretty paranoid, such as when he kills a woman and her guards without any proof that they were Darkfriends. Later in Tear and the Waste, he's seemingly acting normal again. Then the voice of Lews Therin comes, and the obsessive list about dead women. In TWH, saidin is cleansed, so that should have put an end to the development of his condition. Then again, his refusal to allow anyone hurt Semirhage (and rationalizing it as the last remnant of good in him) in TGS is pretty f***ed up.
Not really an unsolved mystery, but what do you think? How much was he affected by the taint, and where did it really show? Or was he completely sane?