@Reynard: Would you be willing to share the different art styles for these?
I don't get why "floating eyeballs dripping with ichor" is acceptable but "bare feet" is not.
While D3 is good at avoiding concept bleed, we don't really know what's behind the hood. Depending on the computing power available in the language analysis part of the image generator, it can be good or bad at identifying words that go together. I suspect Microsoft is using a lot of expensive hardware for this so it's good, but it might not be perfect and
can produce mistakes. That's when you get accidentally get NSFW images.
For example, there is nothing wrong with generating a man with blue shirt and a green tie and black pants, when the prompt was for man with green shirt, black tie and blue pants. It's not what is wanted but that's just the engine collating the word wrongly. There is also nothing wrong with not understanding that someone breathing fire has is head in a camfire while you wanted a dragonlike fire breath. It's just the engine failing at correctly understanding the word salad we call natural language.
HOWEVER, imagine what can happen if you use innocuous words and they get applied to another context. "A girl with bare feet with her hand crossed above her chest" can become embarassing if bare gets applied to another word.
Also, concept bleed also can happen where the prompt is just not precise enough. AI doesn't know the objects themselves. They are just statistically generating something that is often close to the thing prompted and "hope" to get the desired outcome. So, if you give in your prompt no informaiton on the girl clothes, and you just mention "bare feet", in your mind that means she is clothed except for her bare feet. But the AI is drawing bare feet and then statistically decides that the feet is connected to a leg, about which he has no information. Statistically, the AI will decide that the leg should have the same skin tone than the foot (because when he doesn't do this, the meatbag isn't happy) but... sure, next to a bare feet there is a good chance that the leg is covered by trousers. So most of the time, it will draw trousers, even if you didn't mention it. But there is a statistical chance that the bare feet is connected to a bare leg. Then he'll draw upward and look at the crotch... and well, you can see what the problem is.
Even if it occurs only one time in a thousand, Microsoft can't have bing be the latest teenager tool for drawing nude girls and get banned from schools and parental blockers.
So, I think they took measures to prevent anything bad happening in case of goof, which can block perfectly innocuous images.