Only thing I'll add as a data critique, the negative factors are reported as things to avoid. But, in fact, all of the reported on titles actually made it onto the Hacker News front page (1). There are an awful lot of submissions that never make it that far. In fact, the significance of the findings indicate that those terms make it onto the front page A LOT (2). I don't think the negatively correlated terms should necessarily be viewed as failures. Just less successful. My own suspicion is that those titles do draw eye-balls, but someone using titles like those is also likely to be kind of a bad writer, preventing those stories from getting upvotes. It would be very hard to prove a correlation between quality of title and quality of writing, though.

(1) I believe. Hard to tell from the post.

(2) Otherwise there wouldn't be enough data for them to be significant.