We know from all the booing the other night in San Diego when Colin Kaepernick knelt during the "Star-Spangled Banner" that a lot of fans are not charmed by the quarterback's national anthem protest.
And we know from some of the idiotic reactions on social media -- OK, that's redundant -- that there's widespread outrage that the quarterback would have the temerity to protest racism and police violence by refusing to stand, hand over heart, for the pregame anthem ritual.
But here's something just a little unexpected, unless you think a giant jersey bonfire is in the making: According to less than completely transparent data provided by a couple of sources, sales of Kaepernick jerseys spiked in the immediate aftermath of his protest.
Dick's Sporting Goods says its tracking of NFL jersey purchases shows that Kaepernick's uniform top was the league's seventh-best seller for the past week. Before that, Kaepernick jersey sales had ranked 33rd for the period going back to the 2016 NFL draft.
ESPN reports that Kaepernick now has the best-selling jersey on the 49ers, up from sixth before his protest became public a little over a week ago.
"A source with knowledge of sales numbers confirmed to ESPN that more Kaepernick gear was sold last week on the team site than the past eight months combined," the sports network said.
Kaepernick gear has sold briskly ever since he replaced Alex Smith as the Niners' starting signal-caller in 2012. For the most part, Kap-related merchandise has moved regardless of how well or poorly he's played.
For the NFL Players Association fiscal year from March 1, 2014, to Feb. 28, 2015, Kaepernick was fourth in overall gear sales, behind three other quarterbacks: Seattle's Russell Wilson, Denver's Peyton Manning and New England's Tom Brady.
Those hot sales continued into last year, with Kaepernick initially ranked second, behind Brady, among all NFL players.
Kap's merchandise has proven popular despite the fact he ranked 20th in passer rating in 2014 -- behind Buffalo's Kyle Orton, who probably ranked in the top 10,000 of NFL sales -- and 31st last year.
In fact, Kaepernick's lousy performance the last couple of years takes us back to a time when a player's jersey would be burned because they were bad.
Still unknown: How Kaepernick's protest has affected sales of the "police pig socks" he was photographed wearing during training camp last month. We'll bet they're up.