Alt-right internet personality Richard Spencer is probably most famous for his 2016 victory rally at which he and his supporters offered Hitler salutes and declared “Heil Trump!” A year later, he helped organize and personally addressed the infamous “Unite the Right” rally in Charlottesville, Virginia, where marchers chanted “Jews will not replace us.” Given this very public history, you would think that no one would have taken him seriously when he tweeted this yesterday:And yet, countless credulous accounts—many on the pro-Trump right, but also some on the anti-Biden left—uncritically shared Spencer’s posting as though it was on the level.That a disingenuous racist like Spencer would pretend to support Biden in order to get attention and undercut the former vice president is not surprising. What is surprising is how many people still fall for Spencer’s transparent trolling.In reality, Spencer and other white supremacists have a long history of purposely adopting their opponents’ causes and pretending to back them in order to undermine them. That’s exactly what Spencer did in 2018 by pretending to support “Zionism,” when he actually has a long history of hate towards both Israel and Jews, and claims that the Jewish state and its supporters control America.As I wrote at the time, “the alt-right maliciously appropriates the deeply held values of liberals and minorities in order to attack them. This is not because the alt-right shares those values, but because it wants to troll those who do.” In perhaps the most blatant example of this, David Duke left the Ku Klux Klan in 1979 in order to found the “National Association for the Advancement of White People,” a white supremacist parody of the NAACP.How can you tell whether a white supremacist or other bad faith bigot is trolling or being genuine? There’s actually a pretty simple test: check and see whether their latest claim is consistent with everything else they’ve said on the subject before and since. Take Spencer’s purported “Zionism” for example.It will shock you to discover that far from supporting the Jewish homeland, Spencer actually (a) despises Israel and its supporters, and (b) has a long track record of insinuating that the Jewish state and its backers control the American government.Needless to say, whatever your opinion of the people Spencer is “critiquing,” this is not how a pro-Israel Zionist talks. It’s how an anti-Israel racist talks when he’s not trolling and pretending to be something else.The same test easily exposes Spencer’s endorsement of Biden as a sham. After all, Spencer has and continues to support Trump’s policies, from his stance on immigration to Black Lives Matter. Spencer even organized the very Unite the Right rally that Biden has repeatedly cited as his motivation for running against Trump in the first place. The racist’s “endorsement” of Biden, like his support for Zionism, is a costume he dons to deceive and disturb the gullible, who foolishly forget the white hood he wears the rest of the time.As bad actors like these proliferate in our discourse, how should we respond to them? Normal people should just ignore them. Spencer and his ilk engage in this performance for attention and outrage. Don’t give it to them. That said, there are always people who will take the trolling at face value, so it’s necessary for leaders to immediately and pointedly disavow such support, however disingenuous its motivation. Through their condemnations, prominent politicians send signals to their supporters about what is acceptable and what isn’t. That’s exactly what Biden’s campaign did after Spencer’s tweet:The problem with Donald Trump, by contrast, is that he has consistently refused to criticize anyone who praises him, no matter how toxic they might be, from the KKK to QAnon. In this respect, Spencer’s declaration did provide an endorsement of Biden, just not the one he intended.