Dear
Aredhel, welcome to the Downs!
I was very interested in your analysis of your elvish namesake; and my contribution to this debate is that no, I think Aredhel was 'unwise' rather than 'bad'. Her behaviour, both in terms of wanting to go where she wanted and marrying Eöl, was certainly unwise;
but that lack of wisdom ran in the family, in particular in her Uncle Fëanor, who directly caused the deaths of so many fellow Elves.
One of the few Elves of that generation who seemed to gain wisdom over the years was Aredhel's cousin Galadriel, who renounced her chance of taking the One Ring, and who was accepted back into Valinor as a result.
Lindolirian, I don't think Wormtongue was an idiot. Saruman would not have chosen such a person to carry out his delicate plans to undermine Rohan. His plan was to undermine the kingdom by undermining Theoden, but to do so in a delicate manner. The way to do this, both by words and by mild poisons, was to ensure that Theoden would give orders that reduced Rohan's ability to defend itself; but he would not give orders that were either mad, or illegal or unconstitutional; so there would be no case to either set up a regency or dethrone him.