How do you handle "sus" customer interactions?

This might be a strange question for an issue that's not universal, but I find myself in situations with customers sometimes, either at cash or on the floor (especially around current affairs books), where I'm just kind of forced to grin and bear whatever they feel like spilling to a privy audience. Obviously, I know I'm not supposed to directly confront a customer's politics in these situations but, when it comes to totally objectionable sentiments, the vacant stare doesn't always seem adequate either. For instance, the other day a customer was talking to me about the book Money Kings (a business history book about like, Goldman-Sachs and other Jewish-American financial triumphs) and then went on a whole spiel that basically repeated the most over-hashed, gross antisemitic tropes imaginable, literally Elders of Zion-type garbage (not, by the way, affirmed at all by the actual book he was talking about). I've had other customers try to explain how China manufactured COVID (not an uncommon one), gay people are grooming kids, immigrants are evil, [insert notoriously evil historical figure] was misunderstood and smeared by propaganda, etc. I know part of my job is to just ignore these people, assuming that they don't evolve to direct harassment and targeted vitriol, but it feels a bit weird to just tacitly accept their spiels and provide them good customer service. Does anyone else encounter these ethical dilemmas or am I just in a cursed store?