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 often think about the Roman Empire because their concrete had quicklime mixed with seawater, which resulted in a chemical reaction leaving patches of undissolved lime throughout the concrete. Therefore, when Roman concrete cracks, rainwater leaks in, hits the undissolved lime, which produces calcium carbonate crystals which fill in the gaps in the concrete as they form. It's literally self-healing concrete!
This is the reason why Roman concrete is so ridiculously resilient that it can last for thousands of years, compared to the few decades that concrete made with modern techniques tends to last. However, after the recipe for Roman concrete was lost to time, it took us about as long to reverse engineer it: it was literally only earlier this year when scientists discovered that the undissolved lime chunks in Roman concrete were not a mistake or a result of bad technique, but 100% the intentional and ingenious key to the concrete's longevity.
Cement production is currently a major source of greenhouse gas emissions, and this could be greatly reduced by creating longer-lasting concrete with the recently rediscovered Roman method, or a derivative thereof.
...But chances are that most people who spend any significant amount of time thinking about the Roman Empire are not thinking about concrete, nor gender variant history, city planning, bathhouses and latrines, how the misspellings of vulgar graffiti are used to reconstruct the history of the Romance languages, how Catullus 16 was basically the spiritual predecessor to "Ram Ranch", or all sorts of other genuinely interesting things about the wonders and woes of daily life thousands of years ago... But rather, most people will be thinking about sexy muscle men with spears and shields and racist fashy undertones.
Ancient people deserve better than that.
i promise you i am thinking about roof tiles, hypocausts, and pottery on the daily
A lot of popular historical period and period-inspired (various fantasy settings or whatever) fiction tend to revolve around wars and stuff. I think we need more works like Pentiment that tries to connect modern people to the human side of history. Humans in the past were still little weird people like we are today, they just had very different material conditions.
Portland cement and it’s consequences have been a disaster for the human race.
E: I do wanna push back on the “figured it out yesterday” part of the lime cement story though. Builders have known about lime for a long time but concrete is reenforced with steel nowadays. A lime/brine cement would eat through the steel reinforcement in a couple of decades and all those pretty modern cantilever things would fall over.
It wasn’t until recently that we had reinforced plastic rebar to use in the same type of constructions (refer to table 3h for revised tension ratings). That’s why the whole internet is lit up with articles about Roman concrete, because we finally have reinforcement materials to build more with it than a patio grill.
I've never heard of plastic rebar, that's super interesting. i googled it and got "fiber-reinforced plastic," is that what you're talking about?
https://en.wikipedia.org/wiki/Fibre-reinforced_plastic
Yeah all that glass filled polymer and carbon fiber is just those compounds held together with some kind of plastic.
Basalt rebar is the same idea as well.
Tbh a better use for oil than burning the stuff.
i watched that animation of the process of roman road building and it stuck with me. i think i was playing valheim a lot at the time and i wanted to make some intense causeway lol, but i've also taken courses in and helped install a small variety of hardscapes in backyards and small agricultural settings. earthworks and other "built environment" design for supporting human activity is super interesting to me.
i often think about the logistics, materials, and processes of the ancient/pre-modern world. my justification is that the world before the dependency of fossil fuels still has lessons for us, from an engineering and design perspective.
i am not so interested in the philosophy and value system of that era, which i think is the distinction. people who are obsessed with the imagery and pageantry are probably harboring fash tendencies.