There is nothing wrong with being hired to write for someone who provides all the conceptual content, ideas, and research but just doesn't have the skills to write on his or her own. A ghostwriter may not get the credit for the work, but at least they already know this will be the case. There are certainly both pros and cons to ghostwriting, however given the right context, I would say that it is a perfectly ethical business practice.
Ghostwriting is a permissible activity that does no harm to anyone. As long as the ghostwriter is aware that his or her work is going to be used in this manner and is fairly compensated for his or her work, then there is no wrongdoing done to him or her. The person whose name is on the work is paying someone to help them while still maintaining their image as a writer and thinker. The reader still receives quality writing and has the choice not to purchase a work which has been ghostwritten. Overall, ghostwriting does not harm any of the parties who participate as long as all are compensated for their work.
I believe it's a form of cheating. It's like paying someone to do your homework and passing it as your own. I don't see in any way how that is wrong.
Clients of ghostwriters often deny that they use ghostwriters and the ones who do get caught using one (much like Zoe Suggs) get mopey and whiny when someone calls them out. It's irritation seeing people take credit for something that is not their own.
When someone puts their name on another person's work, that is wrong. It isn't the person who is being recognized work. I don't understand why someone would want their work to be passed off as someone elses. They should get credit for their thoughts and ideas. I would want to know whom actually wrote the article.
No, I don't think ghostwriting is ethical, nor do I particularly like the idea of ghostwriting. Ghostwriting gives all the credit to the celebrity or whomever's story is in the book. All of the work is done by the ghostwriter, but that person receives very little credit attached to the book.