This excellent article rewriter tool will thoroughly scan your entire content, looking for the words that it can replace with a synonym. All the words that it replaces with a substitute will be highlighted in the bold and colorful text. By clicking on any of the highlighted words or phrases, you can see the original word, suggestions or add your own word. Also, you can click on the original word to revert or click on any other word to replace.
That’s really weird. I have tested WordAI and Spin Rewriter with Copyscape and the results were always 80%+ uniquness, even 90%+. I don’t know how u spun the content to achieve such low results, but this is definitely way too bad. As for the block spinning, I have to be honest, this is the first time I’m hearing of it and I will have to check it out when I have a bit of time, but generally, yes, in the best case scenario, you would manually touch your Tier 1 content to make it 100% human readable and as unique as possible. For lower tiers, you can do pretty much anything, but again, the better quality of content, the better results you will have. That’s in my opinion and experience.