You’d have thought the standard of decency in American presidential elections couldn’t get any lower – but partisan trolls on the Internet have managed to debase it further this year.

We’re not talking about the official campaigns, though the candidates have been doing their share of mud-slinging.

The McCain campaign, for example, had claimed that Barack Obama championed “comprehensive sex education” for kindergartners, as if 5-year-olds were going to be taught how to put condoms on bananas. Flat not true.

Obama has flung dung, too – as when he ridiculed McCain’s suggestion that “middle class” incomes can run up to $5 million. McCain’s remark was a joke, and Obama knew it. The Arizona senator’s very next words were, “No, seriously . . .”

Those are garden-variety distortions, the kind of nasty twisting of words and intent that happens every presidential election. The real depths of malice this year are to be found on the Web, where a legion of nameless liars is spinning smears out of thin air.

All the candidates have been targets. Obama, for example, continues to be accused of being a closet Muslim and of being indoctrinated in a radical Indonesian madrassa as a boy. The Web is rife with such foul lies about Obama.

Right now, Alaska Gov. Sarah Palin is getting the worst of it – undoubtedly because she’s a newcomer, and slimers on the left are in a panic to get as many lies out on the Web as possible.

FactCheck.org, a project of the Annenberg Public Policy Center, is a respected truth squad. It has documented and rebutted various anti-Palin falsehoods. Among them:

 • Palin supposedly cut Alaska’s special education budget by 62 percent. Actually, she signed legislation to increase funding for special-needs children, in some cases to triple it.

 • Palin was supposedly pushing to ban a list of books from the Wasilla library. Palin did have a “what if” conversation with the town’s librarian about book challenges, and one can make conjectures about her intentions. But the list is a demonstrable fabrication.

 • Palin supposedly supported the presidential campaign of far-right candidate Pat Buchanan in 2000. Like the Obama-madrassa tale, this is hokum; as the mayor of Wasilla, she simply wore a Buchanan button – as a courtesy – when he was town for a day. She supported Republican Steve Forbes that year.

This week, computer hackers broke into Palin’s Yahoo e-mail account and disseminated personal material – including family photos and e-mail addresses – on the Web. It’s not clear whether there was any partisan motive behind this criminal act, but it’s another example of vicious, anonymous, Internet-enabled assaults.

These are intolerable when they target Republicans; they’re intolerable when they target Democrats. Voters, we hope, won’t fall for them.