How does HN keep spam free?

I think this is best answered by a moderator, but it probably boils down to:

1. Self selection bias. HN isn't a huge outlet, and doesn't attract quite as many spammers as other platforms.

2. Quality moderation. Just flip on the `showdead` flag on your account and scroll through the hundreds of [dead] threads.

3. Some level of auto policing. I know that HN validates some level of page history when counting upvotes. (i.e. if you navigate directly to a page to upvote, that vote isn't counted)

Incredibly good paid mods, aggressive spam algorithms, even more aggressive downvoting, and a lot of (justified IMHO) gatekeeping. Nothing you couldn’t do yourself for a million or so to start and at least half a million a year to run, assuming you hire brilliantly ;)