Gotta hand it to Mike Bloomberg. At least we know who he is and what he hates.

American politics at every level is flooded with “dark money” — campaign funding indirectly employed — that comes from people who hide, trying to buy elections without signing their names to the receipts.

EDITORIAL

They and their front organizations may not even be honest about what’s their beef. They might tell you, for example, that they’re great champions of the free market — that’s why they love Candidate John Doe — when they’re just trying to protect some pollution-spewing coal company.

The Koch brothers are excellent that way. They may tell you the truth. They may just as likely, if the truth won’t fly, tell you what sells. And they’re big on secretly funding their advocacy groups.

But Bloomberg, the billionaire former mayor of New York, is as up-front as can be. It’s his money, he says, and he’s going to spend it to support Cook County Board President Toni Preckwinkle and the county commissioners who voted for a tax on sugary drinks. Bloomberg, who always looks very fit, is passionate about the evils of sugar.

That might not work out so well for Preckwinkle. If you’re a local politician, it’s usually best to get your campaign money from local sources. When you don’t, it can be a sign you’ve got serious popularity problems with the local voters.

Mike Bloomberg, that is to say, can’t vote in Cook County.

According to a report by Sam Charles of the Sun-Times, Bloomberg has vowed to throw money into Cook County races in support of candidates who voted for the county’s new penny-per-ounce tax on sugary (and, really, not-so-sugary) drinks. He already has spent $5 million on ads supporting the tax, and now he’s prepared to support individual county candidates in next year’s primary and general elections.

Bloomberg’s enthusiasm doesn’t make the soda tax any better. We still think Preckwinkle and the County Board sold the tax to the public under false pretenses, saying it’s mostly about encouraging more healthful behavior when it’s mostly about raking in new revenue. And we think the tax puts an awful lot of local retailers at a significant competitive disadvantage.

Try selling a 12-pack of Coke on one side of the county border for $1.44 more than your competitor sells it on the other side of the border. As a retailer, you lose not only that sale, but every other sale you might have made if the customer had walked into your store instead of your competitor’s.

The unpopularity of the tax is no longer in doubt. If Bloomberg is running to the rescue, it’s because Preckwinkle and the commissioners who voted for the tax need rescuing. Almost seven of every 10 Cook County voters disapprove of the tax, according to a recent poll, and more than 8 of every 10 say they are less likely now to vote for Preckwinkle.

But, to be clear, this is no knock on the way Bloomberg does his political business. Sure, he’s a rich New Yorker butting into our local affairs, but that’s going to happen. Mayor Rahm Emanuel has collected big campaign donations from the likes of filmmaker Steven Spielberg and music mogul David Geffen. Emanuel’s opponent in the 2015 primary election for mayor, Jesus “Chuy” Garcia, pulled in money from the California State Council of the Service Employees International Union.

Campaign funding from local sources might be preferable to funding from “outsiders,” but what matters more is transparency in funding. Above all, you want to know who’s writing the checks and why.

A classic case of anti-democratic misdirection — where donors opposed a candidate for one reason while pretending to another reason — played out in a 2004 Supreme Court race between Democrat Gordon Maag and Republican Lloyd Karmeier. Judge Maag was thought to be sympathetic to defendants in worker’s compensation cases, so trial lawyers loved him, while Judge Karmeier was more closely aligned with the business owners sued by those trial lawyers.

But that wasn’t an issue likely to excite the voters, so before long some of the bigger donors whipped up the entirely fake issue of who was “softer” on crime.

The ads “were about crime, about beating up the little old ladies, the drug dealers running free on the playground,” Cindi Canary, the elections reform advocate, later lamented to the Sun-Times. “But if you look at the money, on one side it was the plaintiffs’ bar and the other side it was the defense bar. So in some sense you have an election that in some ways was really hijacked.”

Welcome to Chicago, Mr. Bloomberg. This may be a town that, famously, doesn’t “want nobody that nobody sent.” But you’re here, and you’re aboveboard and honorable in your intentions, even if you’re wrong.

And Preckwinkle still has to explain that extra $1.44 hit on a 12-pack of pop.

Send letters to: letters@suntimes.com.