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.
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.
Using Spinbot you can instantly spin (or rewrite) a chunk of textual content up to 10,000 characters in length (or about 1000 words), which is much longer than an average website or freely-distributed article. With a single click you can turn your old blog post or website article into a completely new one, thereby doubling the payoff you get in return for the time and energy you have already invested into creating quality website content. Spinbot is lightning fast as well as free, so there is potentially no limit to the amount of free web content that you can create using this tool.
He saw a trainer nearby and asked why these animals just stood there and made no attempt to get away. “Well,” trainer said, “when they are very young and much smaller we use the same size rope to tie them and, at that age, it’s enough to hold them. As they grow up, they are conditioned to believe they cannot break away. They believe the rope can still hold them, so they never try to break free.”