They didn't care that lies were told because they decided that their top priority was to get their guy elected, higher priority than doing what's right for their fellow citizens or the country. This is the worst aspect of politics, which already has so many negatives. The partisans pick sides and defend them no matter what, no matter how wrong they are, no matter how much it hurts, they assume that the only thing that matters is winning. It's like when the US made allies with some of the most brutal dictators in the world because they agreed to help fight communists and socialists and unions, because they felt that winning that political contest was more important than maintaining honor and decency.
There's also the group that just doesn't care about the lies. Logic and reason are tossed out because they think that the gut feeling is always right. I was on a jury once with a guy like this. All but him voted for not guilty, but he was convinced the guy was guilty. We went over the evidence point by point and showed that the prosecutor had a very weak case. But he just kept getting madder about all this, until he blurted out "well if he's not guilty of these charges at least he must be guilty of *something*". That's how I see a lot of voters, in all political parties, they stick with what their gut tells them.
And then the last group, they can't tell if something is a lie because they lack the ability to determine true from false. Their only information comes from what they are told and they won't bother trying to corroborate or investigate independently. Sometimes they'll justify it by saying "all media lies, so I refuse to believe anything the media tells me" while turning around and believing whatever their Facebook friends say. Other times they just don't know how to sift through information or differentiate between a story with shaky evidence and a story with good backing.
(and it doesn't help that most journalists have turned into walking tape recorders and only parrot whatever they hear politicians say)