We've been over this point repeatedly. There is a narrow band where blood would flouresce with luminol and not with TMB. That means the blood has to be highly diluted. A foot completely covered with blood, yet also diluted blood, must therefore have occurred by placing the foot in an area with water that has highly diluted blood in it.
If it was blood, this could be easily explained by bathing in the bathroom were diluted blood could have been present.
The scientists doing the test said the luminol flouresced strongly, indicating a foot that was bloody. However, it would only strongly flouresce in the presence of non-diluted blood. But the blood has to be diluted because the TMB did not find it. So either it is not blood or the scientist's observation of the test was false. If the scientist's observation was false, or if he lied about what he saw, then we have a problem of the test-taker's credibility. Stefanoni also did not reveal that she performed the TMB test and it came up negative, as was required to do. Now we have an example of obstruction of justice, and not a minor one at that.
In order to believe that the footprints were made in blood, we must believe that the original scientist wasn't doing their job very well (the luminol actually flouresced weakly and his observation was false) or he had an agenda to find Amanda guilty. But if we believe that, then that creates doubt about the evidence anyway. It also raises a large red flag on the reasons why no confirmatory test was done.
The fact that we now have proof that the scientist's booties were flourescing brings additional problems to the test.