Bubbles.
Bubbles marked the point where MJ ceased to use the media and the media began to use him. Eccentricity is not particularly cool even if outrageousness is. Right when it became apparent that Bubbles was more than just another pet in the zoo, is when the creepiness factor began to stir and the point where people became more interested in his antics than his music. Eventually it didn't matter what MJ put out or how good it was. The media relentlessly focused on his oddness. Interviews became all about rumors, not music. Paparazzi didn't care if he hosted charities, they wanted suspended animation chambers and elephant man bones.
This same thing happened to Princess Diana as soon as she lost her HRH title. The media sensed she was weak and began being not-so-pleasant. Rumors about Harry's paternity openly circulated and crotch shots were taken of her in a local gym. Diana quickly learned that she had to keep her mouth shut, always be discreet, and ramp-up her PR to give the media opportunities to make money off of her while she exploited them for her gain. That's the difference between MJ and Diana. Diana realized she had to cooperate, play to her fans to keep her popularity and, thus, her power, and only then would the media treat her with respect. MJ went recluse, isolating himself, failing to uphold his end of the fame game. He went after his record label, he went after the media, and he was completely indiscreet when he should have known that any slip would be blown into a tabloid headline. Worse, he disappointed all but his hardcore fans. He should have gotten out and toured, worked with the best producers to make great songs, and use his power of stardom to force the media into acknowledging that they would need his cooperation if they were going to get the best stories out of him; stories he could spin, control, and use to enhance his image while fattening the pockets of the media. Had he managed to do that, then I can virtually guarantee that there would be far fewer people believing he was a pedophile. Instead, MJ would have been, in the mind of the general public (not just his fans) the victim of horrible people looking to soak a rich and famous guy who loved to help children.