For me the easiest tell is the up front, unprompted, and unsolicited declaration of nonpoliticalness. When someone takes the time and expends the breath to announce how nonpolitical they are, what follows is almost always a rant about how everything/everyone else is too political these days, and that of course leads into something between status quo advocacy and outright reactionary/regressive sentiments for some fabled time before those wicked politics were visible to the nonpolitical ranter. 
People that are hostile to service workers. Some just want to take some ideological stand against tipping when the service worker doesn't really have a choice and needs those tips to survive in the current unjust system in a way where ideological purity gestures toward that service worker just look like being a greedy and sanctimonious asshole. The worst of such people will actually declare, shamelessly, that they believe that service workers don't deserve a living wage. The implications of that are 
worthy.
I may get shit for this, but I'll say it anyway: this hair and beard combo, seen on living people. 
I have yet to meet anyone in person with that look that wasn't a chud.
(If one of you is a comrade with that look, I am sorry in advance for the prejudice and if I ever meet you in person I will atone by buying you a drink or something.)
I think it's much sussier because it has sexual violence throughout along with the genocide business. Shield Hero is sexist but surprisingly close to the (disgusting) average for such fiction once you get past that first episode (which is fucked up pandering to red pillers). Like, idk, think about the typical isekai and it's astonishingly objectifying, to the point that it really feels like the MC views women in the fantasy world as truly being NPCs who mainly exist in reference to his sexuality, or maybe the MC is a Good Guy (tm) but the shot composition and animation framecount demonstrate that the viewer is not meant to have nearly so noble an attitude.
On the other hand, there's the pseudo-isekai Redo of Healer and the actual isekai Slave Harem in the Labyrinth of Another World, both of which are much worse but also essentially soft porn and therefore less likely to be discussed publicly.
Shield Hero is especially bad because its sexism is so close to (the incel's fantasy of) the real world. The titular hero has his life ruined by the dreaded False Rape Accusation and then fixes all his problems by finding (buying) a tradwife (underage slave)
Wow, I knew about the part where she gets renamed slurs but not that geez