Sometimes you just read one caption and everything looks too neat, too balanced, every sentence was actually sounding like some motivational speaker. Real people do not type like that all the time. There are bound to be mistakes, we jump thoughts, add some gist , complain and we even throw one random joke to spice things up. But to say the fact, it is very difficult to know the certainty just by reading sometimes because some people write very polished posts. I have also seen some of them using AI then edit it well until it sounds completely normal. So, you can't really judge based on whether AI helped or not.