How Do I Know A Article Is Original ?

I am interested in buying some articles over in the content area here at Digital but have not ever bought articles/content before from anyone or anywhere. How do I KNOW what I am buying is original/organic? For me to post a "copied" article on any of my sites would have a dire price for me, as of the line I work I do. My reputation and therefore business would suffer greatly!
Also how do I know that if it is original that the seller won't also sell same article to someone else after I buy it?…
How Do I Know A Article Is Original ?

See original post by truivia