Who are these people? Something inconsequential happens and they switch their preference. Do pollsters have them on speed-dial? Do they poll the same people each time Hillary turns sideways? It defies common sense. One reason I tend not to take most polls seriously.

or the Taylor camp vs. her latest throb

IOW, mindless cretins who have no functioning concept of reality

the type who hang on every word of Billy Mays

They know so very little about the candidates or the issues, that any new piece of information can change them.

Maybe it's a bit like the people who decide what car to buy based solely on the ads. Most people only buy a new car every four or five or more years, and in between don't think at all about what is really most important to them in a new car. So when they get to the end of the current car payment, they start noticing the TV ads, and go from there.

Most advertising is simply designed to sell the product, to make you emotionally involved so you'll purchase. Actually providing you with useful and accurate information doesn't matter. Since most people watch lots and lots of TV, and are bombarded with advertising every day of their lives, they look at the political campaigns exactly the same way they look at all other advertising: latch on to one particular "fact" that matters the most, and off they go.

Most people here pay more attention, and assess the candidates very differently. Even so, there was a huge range of opinions on this site about Hillary's walking pneumonia, whether she should have announced it sooner, and whether she was to be admired for trying to power through it. And those differences of opinion were based on both personal opinions on what happened, as well as a realistic (however varying) assessment of the facts.

A lot of people out there aren't at all in the habit of thinking. They just take in whatever they see on the screen and usually parrot back various talking points. So (somewhat depending on exactly how they get their news, and if it's mainly from Fox or Facebook they're often misinformed about most things) it's easy for them to see the Hillary Health Scare (and walking pneumonia is not a trivial illness, despite her campaign's attempt to spin it that way) and decide they'd prefer an obviously (eye roll here) healthy guy like Trump. Especially if they've been admiring him because he "tells it like it is" without bothering to pay a lot of attention to the actual content of his statements.