Devil's advocate: Said artist wasn't some sick fuck, murderer, rapist, fill in your own-ist until some years after some of that art was created and they weren't like that before.
People can morph pretty suddenly out of seemingly nowhere.
And hey, sometimes for the better. I think about the Glassjaw record Everything You Ever Wanted To Know About Silence. I mean it's one of the few albums where I'm like "dude usually lyrics aren't a big deal to me, but this is some vile bullshit that actually ruins the damn record". The frontman himself in time saw it the same way and looks back negatively at his lyrical output on that record. So I guess I can separate the artist in that they no longer stand behind it on an emotional level.
Edit:
Related, but unrelated. Burzum was awesome prior to Varg going to prison. He's a disgrace of a person, but I still enjoyed all his nutjob youtube videos and manifestos. Provided us with good gifs.