With HIS HIStory, (pun intended), I wouldnt want to touch that!! More seriously though, with death always come the forgers, and in a legends' case, more so.
The only way I'd accept an autograph done, or supposedly done, by someone who has passed away before, is if a member of the person's family or estate is giving it to me as a GIFT. It's happened to me once before, when Vicky LaMotta's son Harrison was kind enough to send me a check signed by her, but it has happened.
I really dont comment on jackson because if I speak my mind I know I will get "stick", but signed bedsheets/pillow case ? Cmon , I hope they cant be real.