I don't assume. I observe and I listen.

The problem with a lot of folks is that... they are massive massive hypocrites when it comes to this stuff.

And they catastrophize ordinary harmless interactions into these hyperbolic experiences in their head and make insane conclusions about absolute strangers who gave them no evidence to support their judgements. I also encounter it a lot when dating too. I meet strange women and they start lecturing me about myself... when they know absolutely nothing about me. But the weird fiction in their head they have already written so intense and real to them, that often they totally reject any real facts about me that don't fit the story they have already made up. Especially the past few years I had so many expereinces where people tell me about myself, and I go 'well that's not true, I did x instead of y' and they go 'NO, YOU'RE LYING I KNOW YOU DID Y'. And weird shit like that.

I wonder if OP has legit dealt with mentally ill folks at all. I have. They don't act polite and respect your boundaries, they get up in your face and scream and threaten you. And usually fixate on something bizarre. Last time it happened to me a few months ago it was a guy on the subway who started screaming at me about my boots being gay and how he wants to fuck me because they are so beautiful.