My example was from around college with a Disney adult (I know) who was adamant that Pocahontas shouldn't be counted in the Disney princess line up.

That fixation set an alarm bell in my liberal brain, but I didn't want to think it was racism at the time. But the fixation on using technicalities (not technically a princess in the western monarchy sense) like in this case was just reaching to exclude a category of people in a way that was socially acceptable.

I can see that unbending view of rules and technicalities to be a red flag. The lack of willingness to take a personal stake in a topic and couching your real thoughts in arbitrary rules has been a clear sign for me to watch out. I see it with boardgames too. The excessive rule-following clues me in to a lot of reactionary behavior.

What about the rest of you? What things turned out to be red flags like that?

Edit - Fast forward to present day and this person is no longer a friend and is big into Q, Trump, and covid denialism.