I've run into this a few times lately on Fiverr.com - people want you to "re-write" something. The different aspects I see that come into play are as follows:
Often the content is very well written, and even well known material, but the client wants to use the information for his own purposes, and doesn't know how to talk about the content himself.
The client may have some specific ideas about what he wants to add or not include, but usually doesn't communicate those things, and then is disappointed that the client didn't know instinctively where he was going with the project.
The client only provides one source, but expects the writer to pull from multiple sources, OR the client doesn't realize it's impossible to write a new article on things that are not common knowledge subjects without research and pulling from other resources.
For example, re-write the above sentence... there are only so many ways you can say that.
There seems to be a big misunderstanding about what an original idea is, and how writers function. If you're re-writing one sentence, that's one thing... but it's much more productive and much easier to write from a topic (such as: discuss homelessness and veterans) than to say, "Hey, I found this great article on this topic and I want you to rewrite it so I can use it in my book."
Often, I can't even "re-write" a description or a single sentence to a client's satisfaction. How many ways can you say, this product is a mug? I often think I've done well to engage a reader, and I receive back comments such as, "I was looking for something catchy..."
So, re-writing is now a key word I stay away from, because, for me, that means: A client with poorly thought out expectations, with some agenda they aren't sharing, looking for a shortcut to having their own stuff, without creating their own stuff, and expecting me to read their mind and then create awesomeness. That's worth more than the $5 they're usually willing to pay.