MJ deserves the dragging because he was only a puppet with mediocre songs and talent, who was not liked by a lot of people in this millennium at all, yet everyone started praising him after his death. But I don't generally drag celebrities.
I drag the dead if there's something from their career to drag- eg, Amy's **** live performances or Whitney's whack last couple of albums. It's a bit tasteless to drag the circumstances of their death, though.
If the person was a disgusting human being, death doesn't make them saint. Our president died in a plane crash and he was a xenophobe, homophobe and sexist. What's there not to drag? There are consequences of being a piece of ****.