SEO black hat techniques include spam linking, setting text the same as the background color, meta tag stuffing, keyword stuffing and more. Using SEO black hat techniques may get you a short term boost in SERP rankings, but will eventually get you booted from the Google SEO results.
SEO is an ever evolving field of online marketing. Google focuses on their users experience. If a Google user finds a website from the Google search engine, but has a negative experience on that site, they are more likely to use a different search engine in the future. This is, of course, what Google is seeking to avoid. They want their users to find useful, concise information on the sites they refer. Just because a practice was not a SEO black hat technique yesterday, does not mean it will be okay to use today.
The Google algorithm is how Google ranks the relevance of a website to the search term the user enters into the Google search engine. The algorithm changes periodically. While Google does not publicly disclose all of the factors the algorithm uses, and exactly how each of those factors weigh, the Google blogs do provide insights into how the algorithm functions.
The general rule of determining whether a technique is a SEO black hat technique is to ask yourself whether by using that technique you are likely to boost your SERP results, but unlikely to provide quality content to a visitor who comes to your site through those results. If they page people first enter your site from – called a landing page – is listed high in the SERP results because of tricks you employ on your page, then they are not likely to find the useful information they are seeking. If this is the case, they will likely only visit a page or two of your site and will leave dissatisfied with their experience.
Maximizing the user experience should be the number one goal of all business people who solicit business from the internet. Even if that user does not become a paying customer, if they had a positive experience they are more likely to return to your site when they are ready to make a purchase. Providing useful, relevant information related to their search terms will ensure they are landing on the right page of your site, and are getting the high quality web experience they are looking for.
You should never use SEO black hat techniques to generate leads to your website. Doing so will leave your visitors with a negative impression of your site, and may cost you a customer or client.