I wrote something for the User Experience Professionals Association magazine defining evil design.
When you stop to think about it, the job of interaction designers is about persuading people to do something. We design juicy-looking buttons and place them “just so” on the page to entice people to click them. We remove distractions and streamline processes so that customers glide effortlessly from browsing to buying. We create whole applications aimed at getting people to check in more frequently, diet more effectively, work out more consistently, or do more, more, more of whatever it is that meets our persuasive goal.
Read more over at the UxPA UX Magazine web site.