"I just think it’s worth pointing out that the leaders of the fossil fuel industry, the Koch brothers, have just paid to put up an ad praising Senator Sanders," she said, just before 10 p.m. Eastern time. She didn't explain the comment, or add any nuance about how the ad was simply noting the organization's agreement with a very specific non-oil-related policy of Sanders.

Here's what happened on Google next.

Searches for "Koch brothers" were up 700 percent over normal. Searches for "Koch brothers Bernie Sanders" were up 4,950%.

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Sanders pushed back, arguing that he'd fought against the priorities of the Kochs while in the Senate. Later, he included them in a short description of the interest groups that he had been battling. It's not clear that Sanders knew what the ad was or what it said, allowing Clinton to twist the knife.

"They did just put up a little video praising you for being the only Democrat who stood with the Republicans to try to eliminate the Export/Import Bank," she said, "which has helped hundreds and hundreds of companies here in Florida be able to export their goods and employ more Floridians. So from my perspective, you sided with the Koch brothers."

Clinton's goal -- linking Sanders and the Kochs -- was achieved, however unfair the binding might be. That's how politics works, of course. Clinton wants to increase skepticism about her opponent, and the Koch group was more than happy to help, however indirectly.

But politicians don't always take incoming fire from their opponents. The rising searches for Hillary Clinton during the debate were the result of a question from the moderators.