It's a quick and seemingly obvious insight, but it's one that I'm sure you won't see much of over the next few months.
Yes, the voters can be wrong about something. Obviously individuals can disagree with the electorate on normative issues, for example. Anybody who agrees with the majority on everything is a tool who hasn't thought through the issues properly. You're going to disagree, and it's RIGHT to disagree. Non-voters disagree with voters, for example; they tend to be more satisfied with America and its government, as well as being more progressive. (Shame that they won't vote, or America would be a very different place.)
But that's not the point. The point is that the voters can be wrong on the facts; and to the extent that they're wrong on the facts, they can make the wrong decision for their value set. If they value a lower budget deficit, for example, but they think that deficits are going up instead of going down, guess what? They're likely to make the wrong decision. Not out of malice or spite, but simply because they don't know what the facts are.
That's literally what happened to Clinton. He reduced deficits and nobody realized it. They thought deficits had gone up, when they had plummeted. Anybody who punished him for rising deficits made the wrong decision. They should have rewarded him, but they just didn't know.
The same thing has also happened during this cycle for Obama. He passed tax cuts that nobody knew about and nobody noticed, despite being substantial. He was punished by an electorate who were listening to hucksters whinging about how Obama raised their taxes. They were wrong. They didn't know.
It is those hucksters that are the problem, too. Voters don't exist in a vacuum. They have to get their information SOMEWHERE. Because a lot of voters don't have the time, inclination or skills to pore over quantitative statistical data, or even over scholarly research, they have to rely on someone else to do it for them. And since they aren't necessarily equipped to distinguish between interpretations based on facts vs. those based on convenient fictions, they may well gravitate to hucksters spouting superficially-convincing-but-ultimately-factless bullshit.
Hence Beck and Limbaugh.
If voters are convinced by these hucksters, or by corporate advertising, or by email chain letters, or by "that guy at the water cooler" that a bit of nonsense is true, they'll develop the wrong impression on an issue based on that nonsense. If all those bits of nonsense add up to a great LOAD of nonsense, then many of their impressions will be flawed: not due to evil or naive values, but because of the information they're applying those values upon.
And if someone is a great big ball of false impressions and flawed conclusions, then why wouldn't they make "the wrong decision"? If they knew the whole story, they might believe differently and vote different. They'd change their policies, change their parties, and maybe even change their donation patterns. But they don't. So they're wrong.
Can that happen across an entire electorate? Lincoln's old saying is that "you can't fool all of the people, all of the time". But you don't need to. You just need to fool enough of the people, enough of the time. You just need to give them the wrong impression, based on a soup of false, misleading, misinterpreted or selectively omitted information. You laud their values while you provide that false impression, to build a connection between you; and then when they make the wrong conclusion, you support it with all your might. If you're good enough, with a big enough bully pulpit (like, say, an entire TV network and billions in advertising dollars), you can probably get away with it.
And then, afterwards, you'll have an electorate that will have voted against their interests and values—not because either of those changed, but because they weren't given the proper information to use them to make the decision that they WOULD have made. Irony as political philosophy.
So, yeah, they can be wrong. They shouldn't be. But they can be. And, in this case, I honestly do believe that they are.