Another who doesn't understand the difference between "the aridhol attitude" of Mordreth and "the taint of Shadar Logoth" itself.

The Taint doesn't spread from people to people. RJ said Verin was wrong about that, that Fain doesn't infect with the taint. It's the dagger he carries (or any tainted object from SL) that does, and he didn't have it when he met Elaida and Niall.

Fain/Mordeth is bad news without the dagger. He corrupts those around him, with the Shadar Logoth attitude. It's not "magic" like Mat caught which transformed him and was about to wipe out his mind until only hatred remained before killing him, it's all Mordeth's vicious tongue and what he says. The longer you stay with him, the worse it is. That's what happened to his WC. The Aridhol 'philosophy', not the taint of SL. The same as Mordeth did in Aridhol. He doesn't infect them with the Taint of Shadar Logoth, the way some of his followers who met him since he has the dagger again were infected (Toram Riatin) or the way Mat got infected by the dagger. If you get that infection, you waste and die, as nearly happened to Mat and has happened to Riatin. Only Mordeth himself seems immune.

All Fain did to Elaida and Niall is put seeds of suspicions and hatred about Rand in their minds, with his words, his lies etc. Elaida's not tainted at all, she's just like Gawyn and his obsession that Rand killed Morgase. She already thought much the same about Rand before meeting Fain, Fain just reinforced her convictions about Rand. And it only concerns Rand, not her whole worldview. Put her in Fain's camp for a while like the WC in TSR and she'd end up having the SL attitude. Meeting Fain a few times is not enough.