I used to build negative SEO campaigns for clients a few years back and they were fairly effective, though I don’t know if that’s still the case today. I’m sure it probably is.

yes I think negative SEO is effective. Context matters though, it's probably more effective against newer sites, sites with a weak backlink profile, and sites with more "naturally spammy" content like SEO.

Exactly - a negative seo campaign against... REI’s website as a random example won’t do much.

But it’s not impossible to nuke a new-ish domain or a small business’s domain with tons of bad links through spam services if you know what you’re doing.