I gave this approach a shot over the first few months of this year[1] (although my director didn't have any custom training). The results were interesting, but I'd not call them "art", since they're low-quality derivative pieces. With reasoning traces enabled, you can see that there's not much intent going on. Though they do attempt to include "incidental objects" to reinforce meaning, like in this jungle scene[2].
[1] https://news.ycombinator.com/item?id=48105385
[2]https://www.liamlaverty.com/paint-by-language-model/inspect/...