I don't know for pictures, but I have gotten pretty good at detecting AI in videos. I am noticing these a lot on youtube. Often you can tell, e. g. movements being weird, animals behaving in ways that are only in a short and nowhere else to be found. And some more indicators e. g. youtube insists on showing sexy girls, but the video is clearly "cut" into another video and the surface layers also don't fully align; or some proportions are odd (I don't mean the "regular" ones but e. g. when the biceps looks like semi-hulk, you know something is AI slop). I try to not watch AI slop but sometimes it happens.