Depending on what you're doing black hat SEO can get the job done. If you're trying to promote something you have a limited stock on that you're trying to get rid of black hat SEO can help do that. Let's say you purchased 1,000 of an item and only sold 100 of it before people stopped buying it. You're in the hole and need that gone asap. Black hat SEO can help you sell that within the month and get it all sold quickly and efficiently. After it's sold the site is black listed but you no longer need it anyway.No one would ever choose black hat SEO for his or her website. It doesn't improve the traffic, and search engines detest it alot.