I too believe I'm fairly good at spotting AI writing. You point out some good signals. Its hard to pinpoint beyond what you mention though. One thing I have noticed with AI copy on SN is the needlessly verbose writing style of some AI bots. The complete lack of personality.

I find it much harder to detect AI writing in the business side though because business writing already lacks soul and personality. It is also usually full of buzzwords. Same goes for education writing. In school (unless you are doing creative writing) length is what is valued. AI bots excel at this.

One other signal is when the AI make odd connections that jump out. I was testing something out recently and the AI produced something that a person knowledgeable in field would never say. Something that someone just bull shitting me would say. I knew it was AI but it jumped out to the others I showed it to as well.

One of my first observations after using ChatGPT for the first time was how much our writing in business lacks any soul or heart. How repetitive it is. How robotic. I was impressed with how ChatGPT was able to write faster than me. But was depressed by how programmed I have become to fit into a style of communication that lacks personality.

Machines will always bet humans at being machine like. I think for me, I continue to believe that to beat the machines I should lean into being human and using emotional energy. A machine works on commands. Not passion or heart.