Some freelance articles are designed to broker between a writer and a person needing something ghostwritten for them. In this case the payout is based on an individual's rate and fluctuates a great deal between clients.
Some places have work in specific types while others have no limitations. Some "writing Mills" they are called generically, offer specific types such as articles, mini-posts, and blurbs- these are distinctly different types of writing. The blurb in one mill may be a first person story format while in another it's an analytical 100 word "snippet". In another it could be a description of a product.
Once you become a full or part time professional writer by contracting with companies looking for Independent writers, you will find that individual web site owners may become familiar with you and your article writing and find you.
Personally I seek THEM out and offer a free page write up to show them where their content could go... if they bite I get more work, if they don't I only lost an hour of my life, an investment. Sometimes they don't contact you at all and others they contact you months later when they want to build a new page and need the content outsourced.
They know your work and will call you up to do it, so don't lose faith if you don't get a bite at all- the idea is to get yourself known to as many people as possible and to show your work. If they post it you can use it as a reference to your work- I've written for sites like _____ is what you say. So if they use the content and don't bring you on for more- there is still the resume you built on a variety of site types. You just say I ghostwrote ___.
They could even verify it with the business owner. If they try to jack you you have the original copyright to the content since no contracts were signed no money changed hands... just make sure you print out a copy and mail it to yourself for your own protection (legal copyright). I've never had to do this though. People are generally not jerks when you give them something free!
One thing the writing mills fear is that their customers will figure out who their writers are and bypass them to contract with the writer directly at a lower cost. At least one writing mill I know of restricts the use of numbers in research urls or any notes you provide. Customers used to actually try to find the writer by putting their phone number in there. They would also use the url to hide a phone number! Not sure how they thought writers would catch on to that but I guess they wanted the cleaver ones anyway!
Many of these mills operate in such a way that the writers not only don't talk to the customers directly- but they don't even get to talk to other writers. This is the best way to seal that hole- but as a writer being contacted to do work directly is definitely a win as it means more money- no middle man/woman.