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 didn't want to go into "one health" or "ecosystemic health is human health" concepts because I felt it would derail the conversation, but I think they're important to take into account.
I think it is fundamentally eurocentric to consider that the agricultural and food systems in which one lives aren't deeply linked to one's wellbeing, and that the indiscriminate use of GMOs couldn't have an effect on that.
There's alot of specific ways specific GMOs suck and of course Monsanto gets the wall for shit like round up and the abuse of termination genes (great for research, terrible for farmers)
But so often the protesters are out against something like a scientific research project on soil redmediation, or of course the Golden Rice debacle.