Grey Hat SEO
Gray Hat is an SEO practice that's riskier than White Hat SEO, but one that may or may not result in your site being banned from search engines and their affiliate sites. Generally, Gray Hat SEO practices belong in neither the Black Hat nor White Hat category because the terms of service regarding the issue are unclear.
Grey Hat techniques can be tempting, however we work on long term growth and domain authority, rather than quick wins which could potentially be detrimental in the future.
You don't gain much by getting on Google's bad side, and if you're unsure if a given method is going to violate Google's guidelines or not, it's probably best to avoid that tactic. Every marketer needs to evaluate risk versus reward on their own terms, but with Google's algorithms getting stricter and stricter all the time, your safest route as a business is going to be strictly White Hat SEO.