abstract/minimalist/any heavily stylized image where strokes (pencil or brushes) aren't expected - i cannot tell tbh (if its not cgi looking that is). So where gaussian blur is not slapped on top and nonsense might be expected -

like here

color composition is weird, and some things are wrong with paws/tail/floating head, but that's because i know it's ai thingy, i would completely ignore this otherwise as abstract styling

photo-realistic in general does still have blur slapped on top of it, and weird anatomy/skin issues which require effort to fix (but are fixable already, people just do slop). Also issues with background are fixed with compositing, but as it is slop - people accept blurred background resulting in hyper-focused subject/blurred background which is the easiest tell for now.

Also, for cheap slop humans: if they are small in the image, they don't resolve right in the details (weird ears/eyes/lips/hands), anatomical proportions might be wrong (legs/elbows/neck/body angle/length); skin is flat-out weird frequently (no hairs/too smooth/too wrinkly/just weird), phantom ligaments or muscles where there shouldn't be any (collar/arms)