While organic search has the advantage of being free and can be influenced by your website content, it is limited to the number of people searching for your business or the products and services you offer. Paid search advertising allows you to reach a broader target audience which has more potential customers who may not be aware of your business, all while providing you full control over your messaging and costs.
The Google, Yahoo!, and Bing search engines insert advertising on their search results pages. The ads are designed to look similar to the search results, though different enough for readers to distinguish between ads and actual results. This is done with various differences in background, text, link colors, and/or placement on the page. However, the appearance of ads on all major search engines is so similar to genuine search results that a majority of search engine users cannot effectively distinguish between the two.
In the zero-results sets, Google was still willing to show AdWords, which means if we have customer targets, we can use remarketed lists for search advertising (RLSA), or we can run paid ads and still optimize for those. We could also try and claim some of the data that might show up in zero-result SERPs. We don't yet know what that will be after Google rolls it back out, but we'll find out in the future.
Black hat SEO refers to the practice of trying to trick the search engines into giving you higher rankings by using unethical tactics, such as buying links. The risk is just too great. Even if you enjoy a temporary boost in rankings due to black hat tactics, it’s likely to be short lived. Google is getting better and better at spotting dirty tricks and sooner or later the progress you made will be wiped out by an algorithm update, or worse, your site will get removed from the index altogether.
Well, yes and no. Sure, you can get hit with an algorithm change or penalty that destroys all your traffic. However, if you have good people who know what they are doing, this is not likely to happen, and if it does, it is easy (in most cases) to get your visits back. Panda and Penguin are another story, but if you get hit by those it is typically not accidental.