I forget. Black hat is the bad kind of SEO isn't it? If so, I wouldn't say that The Best Spinner is necessarily a "bad" thing. You have to be careful how you use it though. I've never automatically submitted articles to numerous directories at once, which is one thing that people who use the Best Spinner actually do.
I might use it to automatically help me rewrite sections of articles I written before, though. The main reason why is it does it very quickly. I usually would manually edit each article though and make sure it is different from the others. I wish it would help me create different enough of articles to submit on a large scale but I don't use it for that because I don't feel it does.
How it Works
There is a certain kind of coding called "spin cintax" and it helps create word, phrase, sentence, and paragraph variations of each article. Then, you press the "spin" button and a whole new article or a whole new set of articles is created. This tool should be used with caution.