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.
There are lots of reviews about the product, and many people here are writers that experienced a wonderful time doing their job with the aid of the tool. Most of these people usually say that you dont need to rely on the tool completely to get the job done because that will fail at most times. What you need to do according to the reviewers is that you should learn how to edit the article a bit so that it wont look completely spun since there are some clients that hate this tool.
For a blogger who has to publish multiple blogs on daily basis, it is tough for them to write unique content, especially when writing on same topics. In that case, spin bot tool could be used to avoid self-plagiarism and to maintain the quality on blog posts. As spinbot change synonym automatically but you can pick the most relevant synonym using out tool.