I never receive dms lol. Or barely.
What I don’t like is people who want to force their opinion on you, and won’t even hear you out if you have a different opinion on something. “you’re cancelled”. That’s stupid, no sign of intelligence.
I also don’t like drama queens. Making a big deal out of anything irrelevant. But this is something usually kids/tweens tend to do. I immediately recognise it when I see it. And I usually try to make them see it’s not that huge of an issue, or give advice.
Other than that, I’m nice when people try to talk to me. I also try to explain stuff to them, when a more serious subject comes up. (Well, that’s if the person even keeps talking to me for that long. But as mentioned before, it happened to me too that someone dmd me and said hi, I said hi back and then they ghosted. Wtf is up with those people tho 
)