Unilever's effort to rid itself of influencers with fake followers hasn't made much difference, at least for its Dove brand, according to a new report. And despite the industry's concern about fakes, the report, from analytics firm Points North Group, says spending on influencers continues to snowball.

Unilever Chief Marketing and Communications Officer Keith Weed said in June that the company would stop working with influencers who buy fake followers. But despite that, Points North estimates that 25 percent of the followers for Instagram influencers working with Dove last year were fake, ahead of the industry average of 14 percent. Dove's fake ratio fell only slightly—to 23 percent —by the fourth quarter.

Weed declined to comment on the analysis, saying he hadn't had a chance yet to review it. But he says Unilever will take another look at Dove's influencers and their followers. He also says he believes both the company and broader marketplace are making progress, with social platforms including Twitter and Facebook eliminating a combined 1.6 billion fake accounts in recent months.

Weed acknowledges eliminating all fake followers is probably impossible, but he'd like to get the ratio down to 2 percent or less. They can accumulate without anyone paying, he adds, noting he found many in his own social follower ranks last year—and he hadn't paid for any of them. He'd like to see social platforms develop self-service tools to make it easier to do that cleansing process.

North American marketers spent more than $1 billion on influencers last year, according to Points North. Momentum built during the year, with the fourth-quarter $235 million outlay on Instagram influencers 38 percent higher than in the first quarter. (Points North, which launched last year, doesn't have year-ago comparisons yet.)

The firm tracks all identified sponsored influencer social posts and applies what it believes to be an industry-standard pay rate of 0.3 cents per follower to estimate spending, though it concedes payment terms vary. The firm samples each influencer's followers and applies a machine- learning system to identify the ratio of likely fakes.

Dove's fake ratio didn't even put it among the "most fooled" brands for 2018, according to Points North. That honor belonged to Raw Sugar Living, at 48 percent, followed by Clarins and Amazon's Zappos, at 45 and 38 percent, respectively.