You can never be sure. It's all about faith. You gotta tell the writer not to steal your keyword and not to use it for the sample. The best way is to hire only 1-2 writers as you will have less chance of your content ideas getting stolen.how can one be sure that the writer is not going to steal your kw’s and content idea? That is what scares me the most.
Detecting spun text is a bit trickier. Usually what I do when I suspect that most of an article is spun is find a part of the sentence that doesn't sound like it's spun and search for that on Google and those plagiarism checkers above.Are there any paid tools out there that can check if an article has a chance of being a spunned article or plagiarised?