As I have looked at various Michael Jackson signed items that PSA/DNA has authenticated, I have consistently noticed that many of the MJ items that PSA looked at, and subsequently passed, before Michael's death appear to be non-authentic.
It looks to me like PSA didn't have much of a clue as to what authentic MJ autographs looked like prior to June 25, 2009.
So if you're looking at any MJ stuff passed by PSA before June 25, 2009, beware!
Here is an example of an item that recently sold on eBay for $555. It's a signed Thriller CD. Note the date of 11-12-2008.