That depends on how the artist, the art, the crime, the enjoyment and so on are related to each other.
So take Hitler's paintings. From what I've seen they are quite nice pictures of mostly landscapes. He's certainly a better painter than me and the subject matter and execution looks quite pleasant. Apparently more skilled artists than me criticize the lack of imagination, the "architectural style" that isn't artistic and spiritual enough or that he apparently didn't paint many people and if he did it didn't fit the style and implies he's not that interested in them. So all in all he seems to be a somewhat talented painter and there's no obvious connection between his art and his crimes.
So if someone had a Hitler painting in their room, it wouldn't be their taste of art that I'd be concerned about. My concern would be how that got into their possession? Relatives or themselves being high ranking Nazi criminals receiving it as a personal reward? Paying a Nazi to get it? Using it as a sign of their conviction that is less punishable than a swastika?
So the problematic thing isn't the art itself, for all intents and purposes it would have the same effect as a blank canvas with a single signature or the knowledge of the missing signature.
So there are many perspectives to art, there's the subject matter, the execution, the medium on which it is captured and distributed, there's the artist, the backstory of the medium, the picture, the artist and the art itself might not just be aesthetic it can also be functional.
Like that Hitler painting could serve as a coded "I'm a Nazi"-confession. Or think of a throne. It's not just a decorative chair, it's meant to portrait and enforce a relationship between the user and the rest. The person siting in one is "bigger" figuratively and literally than the bystanders. While he is sitting and relaxed the rest has to stand or even stretch themselves to "be at eye level". So what is easy for one to maintain is hard work for the other, and the constant necessity to "look up to the person" on the throne is meant to make them appear "larger than life", to give the impression of subservience. Similarly some forms of architecture are meant to impress upon you the feeling of being small and insignificant compared to the environment that they subject you to. Or if you take art that took thousands of people countless of hours to make, then the fact alone that you posses something that is equivalent to multiple lifetimes is itself an expression of power and wealth.
So while Hitler's paintings, at least with regard to the subject matter, are unrelated to his crimes, that might not be the case with other creative outputs of his. So idk praising "Mein Kampf" for it's writing would be much more controversial as it is not only notoriously not well written, but more importantly it's an expression of his ideology and worldview directly related to his later crimes. Not to mention that even requesting a copy might support a (neo-)Nazi or "create a market" for that ideology. So it's not so much about supporting Hitler and his art, as he is literally a dead author, but about featuring his ideology and promoting it even by proxy.
Or with respect to functionality one could also mention the other parts of the Nazi aesthetics and whether they are "just art" or whether they are meant to promote an ideology and impress a feeling upon the observer. Like idk whether it actually is uncontroversial if "Birth of a Nation" or Leni Riefenstahl movies should be taught in film schools as case studies of story telling and visual expression or whether the intent of the artist still works even if the people referencing it don't share it.
Whether it's a good idea to cast buffed models with blond hair and blue eyes to match the aesthetics of the Nazis propaganda movies and present a visual cue to them or whether that was a deliberate choice by the Nazis to present the soldiers as role models when in reality they most likely looked nothing like that on average.
So if someone likes the "aesthetics" of the Nazi uniforms because they present people with a feeling of unease and make them change the sidewalk or whatnot, that might tell you much more about their character then just their taste in fashion.
Or how it's no coincidence that the Nazi swastika is tilted by 45° with respect to the Hindu swastika, looking more aggressive somewhat like a shuriken in motion, while the other might give off more of a resting symmetric vibe. Or how that black, white, red color theme is a reference to the German imperial war banner and how the template (red boundary, white circle black text) was apparently used for other "symbols of authority", as well (traffic signs):
Which saw adoption in Germany from 1927 onwards, which is too early to have been influenced by the Nazis but which might have contributed to the art style of the Nazi flag. I don't want to overinterprete these things and especially with regards to the comparison of road signs and nazi flags that's just an observation. But what is a fact is that the Nazis put a lot of emphasis on these details and actively used art as a mean of propaganda. They burned the art of what they considered their enemies and presented their own kind of aesthetic which even if taken out of it's context might nonetheless carry more context than people might want to give it credit for.
Also to get away from that Nazi theme. What about other art that actually involved crimes. Like how Leonardo Da Vinci apparently exhumed the dead to paint more realistic human proportions. Or what about Till Lindemann (the singer of Rammstein) who's poetry on rape has gotten a much more serious context given that he's accused of several cases of sexual assault, rape, drugging and whatnot.
There the art itself is "good" in the sense of being realistic because it might actually BE real. Meaning it's not longer "art" it's "nature". And an enjoyment of art is really an enjoyment of that particular criminal impulse itself.?
Not to mention that it matters how deep you interact with that kind of background at all. Like you could look at a picture of a destroyed city and find it fascinating how the lines and curves form not even realizing what you're looking at.
So it kinda depends on a lot of factors, but yeah if the crime is heinous and you know about it, you should still probably ask yourself some of these questions. What you like about it, why, what it symbolizes to others, what effects it will have on others and yourself and where you draw the lines and whether that is easily possible.