Are these tactics considered Black Hat SEO? Not necessarily. If you are purchasing a domain with keywords relevant to what you offer, such as you having a website www.chocolate.com and purchasing www.fudge.com, then no. Google wants what is relevant for the user, so chocolate and fudge would be relevant whereas purchasing comicbook.com would not be. Either way, you always want to check with an SEO specialist to make sure that you are going about these tactics in the right way. If you do, it can be a real benefit to your business or organization.