The obvious tells are obvious. The less obvious ones fool you so you don't learn them. There's no feedback. You sound like a schoolteacher saying "My students don't cheat on exams. I'd know if they did!" For starters, you can just tell the AI to write in the style of a HN commenter, or whatever.

> tell the AI to write in the style of a HN commenter, or whatever.

This might turn out to be one of those tricks like Ctrl+C Ctrl+V that surprisingly few people discover.