Was pondering it because I was working on one story and thinking of another and comparing sources.
One is the effect of reading a novel and thinking there's a perfect good plot skeleton under these repulsive characters and deeply flawed world-building. You really have to file the serial numbers off to get that type to work, but it can be done. (Unlike when you think they wasted a brilliant plot twist to be tedious. That needs serial numbers filed off, but not so critically.)
The other one is piecing together art inspiration. And not all from the same artist. When a Kinuko Craft and a Arthur Rackham and a Daniel Merriam among others all inspire ideas that seem vaguely to fit together, it can be interesting to put them together -- but no worries about rubbing off serial numbers! (Especially as details of the paintings get rubbed off as irrelevant.) Though for that one I did have an overarching idea -- a city story where the omniscient point of view has no scene breaks, it just skips off and follows a different character when the first one gets boring -- for instance, going to sleep; I shall have to see if that experiment works, or it should be sliced into a more typical structure.