That whole moment where Bashere doesn't quite recognize Mazrim. Davram asks him about it point-blank, and Taim says he shaved his beard because of "the heat" in the South.

Well, Taim knew already the trick of ignoring heat! He teaches it to Rand right away, over the next few chapters! Why would Taim shave his beard from the heat, and end up looking so different, if he knew how to ignore the heat?

Remember what they said about the Illusion trick: it works best when you stay closest to your own appearance. Well, as a woman, there's no way that Arangar is ever growing a goatee again. This could be a huge problem for maintaining an Illusion. Taim's odd appearance makes the most sense if it is due to a FS making their own appearance approximate Mazrim's.

I'm not saying it's certain, just that a good case can be made. The biggest wrinkle I see with this is something that is yet more evidence that Taim is from the AoL: Taim's odd emotions when Rand presents rank insignia to the Farm. Taim is furious - raging, really - when Rand pins him with the Dragon; Mazrim seems to be about to completely lose it.

That moment seems way beyond a mere Dreadlord who's being forced to play nice. A current age DF might not be that annoyed by the subterfuge, but a real AoL Chosen *would* be angry like that. To the FS, these symbols have real and definite emotional resonance and connotations. But Mazrim's emotions in that one chapter also speak against Taim=Arangar.

See what doesn't quite sync up is that when Taim observes Rand muttering to himself, he becomes concerned and actually supportive of Rand; Taim states that Rand "must hold on," or words to that effect. From what we've seen of Arangar's personality, that moment does seem out-of-character.

Still, as much as it might be Arangar, I'd say that Osangar is a bad choice to also play as Taim. Simply put, their positions would require them to be in the same places at the same times. I don't think anyone in the WoT can pull that trick off.