does Black Hat SEO still work?

If you actually use your head when doing SEO, then it works perfectly fine. PBNs and guest posts are still strong as ever. I know maybe 3 people tops who got somewhat hit by the recent updates and reasons were overoptimization. Like every single time there is some update shitstorm happening, this is the cause. Don't try to balance on the edge, play it safe and you will be fine.