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.
Quality readable content is key here. Google, for example, will recognize that people are leaving your site soon after arriving if they perceive that your site or blog is full of junk content. This is called "bounce rate." If your bounce rate is high, then people are quickly leaving your site. But for the sake of your business, to build your online reputation and brand, you want people to visit your site, stay for a while, and then keep revisiting over the long term.
Readable And Unique Content – the recommended settings for this one are the same as for the one above with the only difference being the change of the 1st input to “Readable”. This will create more unique versions of your content while still keeping a high level of readability. Generally, this is the best setting as it gets a good balance between human readability and uniqueness of the content generated.