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’m in a union, and it’s one thing to shit talk our union leadership (they kinda suck and are entrenched), but there are a bunch of people in the union who fairly regularly shit talk the very idea of unionization (management fuels these sentiments by giving our non-union sister workplaces better perks). Also a bunch of my coworkers either promote corporal punishment of kids or proudly declare that they practice it. Got so mad about the jovial discussion of child abuse in a conference call once that I had to go outside.
Both of those are ENORMOUS red flags.
“well I was beaten as a kid and I turned out fine”
I wasn’t beaten as a kid and turned out fine, so I guess all other things equal they just like beating children since it’s evidently possible to raise a kid just fine without it
In the third grade I fell and broke my arm but I turned out fine. Obviously this means that we should break the arms of every third grader.
That sounds like something the Union should act on since here deliberately differential conditions between union and non union shops slwould be something the Ombudsman would be quite interested in.