What are the risks of low-quality or spammy link building in SEO?

Google penalties as a direct result of link building are becoming less common, unless very spammy tactics are used (links from obvious link farms, hacked sites, cloaking, etc). There is a greater risk of getting a website's pages 'stuck' in a certain range of SERP positions for months or years, even though 'natural looking' link building is carried years after the risky tactics have been in place. Another risk is burning through one's budget without seeing any change in positions, or worse, having incremental declines until you notice that the site has become 'sandboxed' in a certain range of positions, site-wide.

Low quality links violate Google guidelines and can lead to penalties and de-indexation as Mark pointed out. It’s a shame that there are still agencies that pedal this type of service. Give a wide berth to any agency selling paid link building strategies or PBNs. Ignore any emails that start with ‘build links with high authority sites’. The best quality links enhance the user experience leading them to a destination that is relevant and trustworthy.

Agree with Patrick here. Penalties caused by off page activities are rather rare. Think about it, if you are certain that a specific action can cause penalties or bring any negative impact people would do this to their competitors and become #1 in a day. The bigger risk with any of that is that it wouldn't move the needle and will be completely disregarded by search engines.

Google has been very careful with its wording around this. Specifically, Google says they devalue or ignore "spammy" links, that is, they don't apply any kind of "negative" to your site purely based on those links. However! They have also talked about the "overall reputation" of your website, and this is where things get more interesting. There will be easily detectable "good" links and easily detectable "bad" links - and a lot in the middle that Google will be on the fence about. I believe, that if you have lots of "bad" links, then you lose the benefit of the doubt for those "on the fence links". Just like how you're less likely to believe a tall story from someone you know lies a lot, vs. someone you consider to be honest.

Probably, the only situation in which you'd have to recover from low-quality link building is if your website got a manual link-relate penalty. To fix it, you'll need to: 1. Check if your website got the penalty. You can do so in Google Search Console > Security & Manual Actions > Manual Actions. If you get a link-related penalty, you'll see "Unnatural links to your site." 2. Find the low-quality links that are harming your website. 3. Disavow those links with Google's Disavow Links tool. Be careful when doing this. If you accidentally disavow "good links," you may harm your rankings.