Any article rewriter or paraphrasing tool basically scans through the content you provide it in order to look for all the words that it can replace with suitable synonyms or substitutes. Every replaced word will appear bold and highlighted in a colorful text. Clicking on the word will give you details such as original word or other suggestions, you also have an option to add your own word. By clicking on the original word, you can go back to original.
He saw a trainer nearby and inquired why these animals made no effort to get away and just stood there. “Well,” trainer said, “when they are quite young and much smaller we use exactly the same size rope to tie them and, at that age, it’s enough to hold them. They are conditioned to believe they cannot break away, as they grow up. They believe the rope can still hold them, so they never try to break free.”
I've ranked websites in the past with spun content, and now they are still on #1 position of google. First year (2014) google found me because my spun was really bad, many paragraphs were just copied and my position drop from #2 to around #20 after a panda update. Later I cleaned all my text with better spun (I didn't buy any article!), my ranking went up again, and with more backlinks I reached #1 and it is still there
It looks like the creators of Spin Rewriter 9 .0 have really put a lot of work into creating a piece of software that creates readable content. However, Google isn’t stupid and there are a lot of things that can go wrong when you are trying to “manipulate” Google into giving you more traffic. Google hates spam, badly written content and duplicate content. These are all things that Spin Rewriter 9 .0 is capable of creating. You simply can’t trust a piece of software to write content for you in my opinion.