If we're talking about separating art from the artist, I was a Lostprophets fan back in my teenage years and I can't even stand it to hear to the lead singer's voice anymore. He's a fucker which I hope rots in jail, and trust me, if you decide to see what he's doing a life sentence for you'll probably agree with me. You've been warned.
Stone Roses and The I.T. Crowd? I can still enjoy the work somewhat, but I won't deny Ian Brown and Graham Linehan can get fucked for all I care.
Lovecraft and Sugiyama? I'm really not gonna judge people from a century ago having terribly outdated views. I don't support their mistakes in any way but they did much less damage than any of the people above.
Context, y'know? I'm not going to treat an idiot like a monster, but a real monster or someone who's actively trying to make things worse will get no sympathy from me.
J. K. Rowling did more fucked up things than Sugiyama. I can let it slide for a 90-year old Japanese man, but not for the British writer which harms her own fans. Context, goddammit.