Dead smile of someone who had too many pictures taken of them as a child. I like to think I preserved my authenticity by being a little monster during pictures as a child.
Hanlon's Razor and all that, but I just assume that's to drive up interaction in the post.
Rant/ramble ahead, you can skip:
By misspelling something, or just doing/saying something that common sense should say is wrong ("life hack, I just discovered this thing that literally every 5 year old already knows about") you will draw out all the people who are genuinely trying to help, people who just can't help themselves but smugly correct someone, people who THINK they know the right way but aren't sure, people who claim to have never seen the right way before, and all the bitch fights such comments produce.
The increased interactions make the post do better in algorithms, which means it goes out to more and more people, who continue the cycle.
My wife watches short form endless scrolling videos despite knowing how bad those are for your mental health, and some of the people she stops to watch are CONSTANTLY pulling the "common sense says otherwise" one. Like my dude you did NOT just figure out in your 20s that you can wait for the shower to warm up before you get in. Literal toddlers know better. It's such a simple thing, I genuinely do not believe anyone in their 20s just gets in the shower while the water is still cold because they never figured out they can wait for the warm water. But hoooo boy did their video take off and have millions of views, and thousands of comments about how wild that is.