Bad was live, Dangerous was about 75% live, concert in brunei 1996 was about 70% live, he apparently got sick for the history tour. He had problems with his lungs due to laryngitis. But he recovered. He did acapellas at the ends of songs, he did the medley live and wanna be startin something. You could hear that his voice was off during the history tour.
He lip synced the concerts in 1999 but did do long acapellas at the ends of them.
See here it's lip synced, the live bit at the end after he talks is just beautiful but you can hear his voice is so much stronger than in history
http://www.youtube.com/watch?v=zZc6VZmbkJU
EDIT wow I just watched the one in munich which was performed after the serious accident with the platform and you can hear how in pain he is when he does the last bit live. You can even hear him gasping in pain at the end. Poor Mike, that accident contributed to his medication addiction during the 2000's. Terrible, terrible accident;
http://www.youtube.com/watch?v=CjNh-90aUJE
I'm not sure why he did lip sync because when he DID sing he sounded amazing. He was live again in the 30th anniversary special.
This is my fav concert as all the fans here know lol but it's from a special free concert for the Sultan in Brunei in 1996 before the history tour. He did a couple of it lip synced like Thriller, black or white and man in the mirror understandably as he was also dancing at the same time,
He MAY have done some history concerts live but we don't know because it's not all on footage.
He loved to perform, but it was the cause that drove him. The fact that he lip synced in history is not a problem to me, because he did some of the most epic dance moves and visited hundreds of hospitals and orphanages.
http://www.youtube.com/watch?v=jy0Y4AP3jZM
PS you can tell if it's playback when the backing singers are him. He did his own backing track.