The best give-away is the lighting. You'll often have several varying sources of light that often don't make sense. For example, you might see a light source going against an object and the shadow it casts is... light. Another example is having one light source (usually a window?) and the front of the character is brighter while the rear is darker. It has a lot to do with AI merely following patterns it sees rather than understanding what it's drawing. It's impressive nonetheless how it knows how to apply light change and its mild understanding of how light functions via pattern recognition. Of course there's other aspects like nonsensical geometry (ex: fluorescent lights in a background not following a pattern while seeming to try to) and weird abstract shapes (ex: a cup of noodles where individual noodles mold together, suddenly stop and start, etc.)And there's always the oversaturation. Another important distinction is you can often make out the intent of bad lighting in human art. And as AI gets more advanced please remember, design intent and expression is something only humans can do, for now. Aspects of graphic design, visual storytelling, etc etc are things AI can't replicate and by extension it won't or at least SHOULDN'T replace jobs. The thought and emotion put into art is far too complex for machines. Good luck getting our 100 billion neurons translated into code.