I have vouched for dead initial comments too, but usually there was a clear reason they were like that, like a link.

I believe that happens when HN suspects the account is from a person who was banned previously, based on IP's and/or some other heuristic. I've seen dang say something like "If you create new accounts to break the guidelines, eventually we just start banning your new accounts."

Perhaps! It might be that these people were unfortunate to share a network with someone malicious (maybe a university, or a company) and this dooms their initial comments.

Is it really a shadowban if you could vouch for them? Shadowban is when the poster sees their stuff looking normal and no-one else (modulo mods) sees it at all right?

By default, nobody sees those comments–you have to go to showdead in your profile to enable it. I keep it on because it gives me occasional insight into the dregs of the site and the effort that goes into moderating it, but also lets me save the insightful comments that get killed (or, very rarely, erroneously flagged.)

Right, I showdead for similar reasons. I figured that shadowbanning would prevent even showdead from revealing those comments, but apparently not: https://news.ycombinator.com/item?id=23686672

I don’t think there is an actual “shadowbanned” on Hacker News, I’ve just seen various stages of banned/flagged/dead users. I mean, I guess I wouldn’t know if there was, but I’ve never heard anyone mention it so…

That's what I thought too, that it was just regular banning. But 'dang says shadowban, and [1] implies he does mean the type where the user doesn't know.

[1] https://news.ycombinator.com/item?id=24790627