Well I guess no one wants to delve in to the darker corners of the SEO discussion :)

hehehe, i'm not sure there's much more to say.

I don't believe for one minute that it's gone away because there's so much that can be done to help poison a site. I very much doubt anyone will want to admit to doing it.

For me, my focus is on the opposite, in that it's trying to do the best to market the site I represent.

In many respects Negative seo is really hard work. Criminals aren't that industrious. :)

Well I did some digging (syphoning many many pages of black hat forums) and it turns out that most black-hatters recommend tackling a new competitor with negative SEO, meaning building links without spamming, but with low quality and direct keywords in the anchor, like few hundred per week. After a month, if they do not have an SEO to help out, Google Penguinizes them. So basically they do 2010 SEO techniques in 2016 for new competitors before they gain traction.

Others make gateway pages from premade templates and invest in cheap domains then start linking those to the competitors. Soon enough, the gateway pages get shut down and many claim that this often results in "soft" penalty to the main site you target.

Spamming huge number of links is considered obsolete as Google just ignores those as obvious attempt at negative SEO.

My site was affected by negative SEO from a competitor when Penguin first hit. I managed to remove most of the poisonous links by signing up to the linking sites and then blocking them. The site hadn't recovered when the Disavow tool became available, at which point I disavowed everything that looked faintly suspicious.

Although the site has partially recovered, I think things have moved on since 2012, and although I still get spates of suspicious looking links I haven't bothered with the Disavow tool for a long time. I suspect that Google - rather than anything I have done - is responsible for the fact that whatever poisonous links there were are no longer having any observable effect.

My view, therefore, is that "building links without spamming, but with low quality and direct keywords in the anchor" is probably pretty ineffective now. SEO is no longer "gaming the SERPs" by another name.

My site is old and established, so simply employing best practice generally works well. How I would get a new one to rank is not as clear as it was when I started out, but I certainly wouldn't use outdated negative SEO techniques on other sites as part of my launch strategy. Almost any other use of my time would have more value.

This year's cause célèbre is zombies. Discussions of negative SEO are sooooo 2015. :-)

Google slaughtered small businesses by burying them so deep in their index nobody sees them. All that's left are Fortune 100 companies, which are probably whitelisted or are large investors in Google. Knowing this, why would anyone negative SEO a whitelisted website or some mom and pop that's on page 10 of Google's search results?

All the kiddie hackers are playing Pokemon Go

Spamming huge number of links is considered obsolete as Google just ignores those as obvious attempt at negative SEO.

Perhaps Google considers huge numbers of links an attempt to manipulate their algo, so disregards the links having absolutely nothing to do with negative SEO.

It's that correlation!=causation thing which isn't well understood.

It's that correlation!=causation thing which isn't well understood.

Google's algorithm is based on correlation. It isn't necessary to know whether there is a causal relationship: correlation alone has predictive value.

If most A's occur when there is a B the reason is immaterial. All Google wants to know is how likely it is, when observing a B, that there will be an A.

Since Penguin was first launched I think Google's recognition of negative SEO has improved to the point that most crude examples of it can be recognised by correlation, so care and subtlety are now required to have any effect. The correlation between negative SEO and care and subtlety is probably fairly low.

Site A has 100,000 links pointing to the home page.
Site B has 10 pages each having 10,000 links pointing to them.
Site C has 100 pages each having 1,000 links pointing to them.

Which is the spammer and/or victim of negative SEO?

It could be all of them or it could be none of them, numbers of links by themselves doesn't mean much. Breaking news, viral video, older established site or pure spam could all account for it.

I've sometimes wondered whether the reports of negative SEO were just collateral damage. If a person had a travel site they wanted to promote, it would be pretty simple to buy an expired domain with a lot of questionable backlinks, 302 it to good reputation travel site A for a few months, then 301 the expired to the travel site they want to promote. Travel site A would see a rise in questionable backlinks for that period of months plus some.

Without considering the ethics, it would look like the reports of negative SEO while actually being someone just washing links. Or would that be considered a crude example?

I thought link washing was an obsolete mechanic and does not work anymore? I was pointed to a forum discussion where the flavor of the month was to make negative SEO, via pointing links from directories with ccTLDs. It takes a lot of manual labor, but the effect is "gaming the system" that is not as obvious, that has a better chance of penguin slap. Did not have the time to try it on one of my guinea pig websites.

@Nutterum
I've read countless case studies where people have stated they are going to do the definitive test of expired domains, redirects and SEO benefit. Virtually all state there is no benefit to redirecting expired domains.
I agree 100% with those case studies, but not for the reasons they state. I currently happen to own one domain I can't do anything with. It sits, with reasonably new content, on it's own domain, but Google won't index any pages. I'm somewhat surprised because there isn't any obvious issue with it, but I have no interest in doing reconsideration or doing anything else with it unless Google starts indexing. More on that later.

You've already figured out that negative SEO is something people fear, but it really doesn't make much sense as a tactic if you are looking to gain position over someone higher in the SERPs. If you are looking at a window longer than a few months, the effort, energy and money is much better spent on content and user experience. If I was operating a search engine, I'd want my users to find sites they were happy with and spent lots of time exploring.

Be that site. If you have users that are happy with the site, they'll be sharing and bookmarking, traffic will grow and any negative seo will not have impact at all. Too many positive signals. Dragging other people down doesn't make your site stronger, a better focus it to make your site as strong as possible.

Going back to the concepts in my first paragraph, you can't really expect that people who just jumped in to a concept will fully understand the concept. So, they'll screw it up, then say it has no value. I'm good with that, I'll just say there is a very significant difference between dropped and expired domains, I don't believe I've ever read a case study that even mentioned the difference.