I have always had an "agnostic" position on the OJ case. I have no problem believing that OJ did it. I also have no problem believing that the LAPD planted evidence to improve the case. I mean, everybody on the LAPD knew that OJ was guilty, so what is the problem with helping the evidence along, to guarantee that a murderer gets convicted. In golf it is called "improving your lie", meaning moving your ball out of a divot or up onto the top of the grass. Many golfers don't consider this cheating. I think that many Policeman don't consider manufacturing evidence against an obviously guilty suspect cheating, since the perpetrators of crime have so many legal advantages and the Police's "hands are tied".
The question to me always was, has enough evidence been fabricated to point to an innocent man? That is the problem. From a jury's point of view, once any piece of evidence has been shown to be manufactured, the all evidence must be viewed with suspicion.
To be specific, the chain-of-custody and timeline problems with the OJ blood samples always struck me as being suspicious. Also, finding one blood soaked glove at the crime scene, and another at the house, especially when both gloves were found by the same Police Officer, always struck me as just too cute.
I felt the investigation was botched pretty thoroughly.