Question

persuading your audience to take some action, aren't you being manipulative and unethical?

Answer 1

I don't know if you are or aren't. You'll need to post what persuasive essay/letter you've written or are analyzing for anyone to be able to see if there is manipulation and/or dishonesty in it.

Answer 2

This article might help you decide:

http://www.members.cox.net/dagershaw/lol/InfluenceMorePrinciples.html

I hope this helps.