Bigots and fascists are basically like mold, they'll get in anywhere there's a crack or a structural defect or a place that's been left unmaintained or untended and then they become really hard to dislodge. In social terms that means like exploiting edge cases of rules, or congregating in places most people aren't looking, or finding the right way to manipulate language to trick people into internalizing and/or perpetuating their vile shit. Unfortunately, we can't - currently - deal with them like mold by just extirpating them, so instead that means building robust community structures and throwing them the fuck out whenever they turn up.