Interesting Topics Are Pragmatically Inappropriate

"Hello! Oh, I was greeting the mites in your eyebrows! Did you know that there are two species; one which lives in hair follicles and one in sebaceous glands?"
What would you do if someone said this to you? If you said it to me, I would probably say "Yes, I did know. Did you know that there are about three pounds of friendly bacteria in your intestines?"
 However, when I actually said this, the response I got was more like "Eew! That's so disgusting! I'm going to rewind my brain so I'll have never even heard that!" It was obviously a social mistake.
I suspect the lesson learned is 'don't choose conversation-starters based on what you yourself would say in response to them'. Especially if one of your favorite things is collecting alarming facts about microorganisms…

But what is a good conversation-starter? Certainly not: "Did you know you can get flesh-eating bacteria from a pinprick?" or "Watch out for parasites in the water!" or "You'd better watch where you're going, because there's an invisible Klingon warbird somewhere around here." All those are considered inappropriate.

 It seems to me that neurotypicals start a conversation by boring each other with obvious comments about the weather. Then they compliment each other. Then they ask each other "How was your day?"* Then they bumble around for a bit before finally getting to whatever point they need to discuss. This makes no sense to me. Everyone can see if the weather's nice, and nobody really wants to hear about my day. And what if it's urgent? Wouldn't it make more sense to start a conversation with "Hello. We need to discuss [subject]"?

 When talking, neurotypicals don't stare around to see if someone's sneaking up behind them; they look at the other person. How will they know if someone is about to sneeze behind them and propel germs 10 feet into the air? Everything I do makes sense to me, although it may not make sense to you. But we're even in that respect; neurotypicals do things that seem absolutely pointless. So pay attention neurotypicals; you're just as strange to me as I am to you.

*I learned these things at pragmatic speech therapy, but I never remember them at the right time. And if I did, I probably wouldn't use them because I can think of much more interesting things to say.