AI is only good at a subset of all possible images. If you have images with multiple people, real world products, text, hands interacting with stuff, unusual posing, etc. it becomes far more likely that artifacts slip in, often times huge ones that are very easy to spot. For example even DALLE-3 can't generate a realistic looking N64. It will generate something that looks very N64'ish and gets the overall shape right, but is wrong in all the little details, the logo is distorted, the ports have the wrong shape, etc.

If you spend a lot of time inpainting and manually adjusting things, you can get rid of some of the artifacts, but at that point you aren't really AI generating images anymore, but just using AI as source for photoshopping. If you just using AI and pick the best images, you will end up with a collection of images that all look very AI'ish, since they will all feature very similar framing, posing, layout, etc. Even so no individual image might not look suspicious by themselves, when you have a large number of them they always end up looking very similar, as they don't have the diversity that human made images have and don't have the temporal consistency.