I have to say that I do think that Rand's dealings with Taim and the Black Tower are pretty stupid, and annoying. The Forsaken have taken hold of many of the power centres in Randland through subterfuge, and you've dealt with a few already, and you don't even suspect that there may be something fishy going on with Taim? The age of Taim, his knowledge, his skill in the one power, his lack of madness, his attitude and his mannerisms don't even pique his curiosity! He's usually paranoid and suspicious about every one else's motivitations, but lax when it comes to this super powerful channeller and his destructive weapons? He just uncritically hands over so much power and responsibility to Taim and leaves him to his own devices! Either the character of Rand is incredibly naive in this regard, or is just a plot convenience by Jordan.

Elayne, for various reasons. For one, her obsession with hierarchy and dominating other human beings is pathological - even the Forsaken aren't that concerned about power. Secondly, her conduct and attitude towards Mat, for example, laughing at him and mocking him after he was raped by Tylin, and her general ungratefulness and lack of human decency. Thirdly her general recklessness and irresponsibility, as well as lack of remorse for her stupid actions, actions that she was told again and again that were bad ideas before she did them.