Spin Rewriter 9 is probably the best product in the market… I get great EPCs promoting it and, what is most important to me is that my clients actually love the product. Very low cancellation rates & practically no refund rates. All around it’s a fantastic product — if it fits your business at all, then you definitely have to get on board & promote it!
Imo it is not possible for google to detect properly spun content, it is not worth computing power it requires. They can do this using ngrams for example, but it is uses a lot of queries. And for example article spinner I coded beats this algo, so google cant detect that the content is spun. Manual spinning is also good but it takes more than 30 minutes per article.