I remember seeing an interview with her on (I think) MTV where she said that Michael had almost no personal contact with any of the other musicians, singers and dancers. She said that she doubts if even by the end of the tour he knew that her name was Sheryl. But she also said that he was a friendly guy who treated everyone with respect.
Most of her negative comments about her experience on the Bad tour have been about MJ's manager Frank DiLeo who she says always tried to talk her into going to bed with him. He threatened to fire her if she didn't and he promised to make her a star if she would give in. She even wrote a song about the experience for her debut album.
http://www.youtube.com/watch?v=ZOzPWcphQ1M
Asked whether despite everything the Bad tour was a worthwhile experience for her she said, yes, because every concert had it's magical moments and Michael would always do something that made you think, "how did he do that?"