If the field is fractured, a surprisingly small group of fans can push a highly disliked candidate to the top of the heap, and once that happens, the inexorable logic of the electoral system can make it difficult to reverse. (I'm thinking here of Trump, of course, but Clinton is almost as good an example.)
http://news.gallup.com/poll/203198/presidential-approval-rat...
My point is, if popularity 2+ years before the election was any guide, then we would probably be talking about how weird it is to have a third President Bush right now (I still remember headlines from 2016 about "Bush surges to 2016 GOP frontrunner"). A year later and Jeb was an embarrassing fizzle.
I have. More specifically, I've seen a bunch of posts criticizing the criticism of her potential candidacy, basically for ruining the good vibes from after her speech. This might be another filter-bubble effect, too. I know a lot of people who are a certain kind of progressive activist.