When you integrate Perfect Tense with WordAi, Perfect Tense will check any text you spin for grammatical errors. Perfect Tense will then add those spelling and grammatical errors as synonyms. This means that your spintax will be more unique and more readable. When using Perfect Tense with WordAi, your spun content will often end up even higher quality than the original.
Google is getting VERY good at catching spun content so you'd better be talented at manual spins. If they DO catch you, of course they'll spank you... and hard. So anything you use spun content on is inherently AT RISK. Worse yet... Google gets better at finding spun/poor content every year. So in the longrun you're screwed. I'd weight your other options and see if you couldn't find a cheaper source for manually hand written content.
Well, most writers write fresh content this way, except for the spinner chief part. Instead of just copying whatever comes up on the first 5 spots, you could curate the best writeups on your topic, put it together and try to improve whatever is already there on the internet. Once your new post is live, go email everyone who has linked out to the sources you used and tell them you have a better one just published. You may get some solid links this way.
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.