For the most part, having the right search terms is important. It isn't always the whole picture, though, If you write about, say, Gary Coleman today your Hub could might (might) get traffic because you go with the right search terms, but there's a good chance not too many people will be searching for Gary Coleman three weeks from now.
So, there's the "flash-in-pan" terms, and there's "evergreen" terms.
There's also the matter of your Hub needing to be unique. Chances are "zillions" of online writers will be heading for the Gary Coleman-related words in the next couple of days. That means more competition for any Hubs you do that with. If your Gary Coleman Hub is on page 50 out of 100 zillion other articles about Gary Coleman, that won't do you much good.
The one thing I've noticed about the Hubs I have that are on page 1 on Google is that they tend to be particularly unique. Hubs that look like every other article out there on the same subject aren't as likely to do well (at least based on what I've seen).
What I've noticed about "the unique thing" is that a Hub that looks like a "perfectly professional" article about one thing or another may not rise to the top. The ones I have that have risen to the top are ones I think are kind of strange, because I just kind of did my own thing and didn't try to write "yet one more article on the same thing". The grammar in the "strange" ones is still my best effort, so it isn't like I "slopped them up", but they're just kind of unusual and not-at-all-"standard" (to the point where I'd be a little embarrassed about the "unprofessional" style).
So I think you need both the "heavily searched" words (and evergreen ones can pick up traffic over time, rather than have it dwindle) and uniqueness. Something that's helpful in some way is even better (and pretty important). So are any signs that people like your Hub, comment on it, link to it, etc.