Veracity/Accuracy of PAS Findspot Data

There's an interesting discussion ongoing at the moment on the HERFORUM at Jisc about including PAS records into HER records. Some HER officers have questioned the veracity/accuracy of PAS findspot co-ordinates. Dan Pett defends his organization:

I'm sorry to hear this is your view. The Scheme's staff, managers, volunteers and finders have worked very hard since 2003 to improve the veracity of the find spots that we record.

Now how can they do that if its the finder who is supplying false data? But then I think PAS see the term "veracity" of information from artefact hunters and collectors a slightly different way: "Out of over 1/2 million records, only 48,264 now do not have any coordinates attached" (by the way, is that not about ten percent of them?) What measures does the PAS have in train to determine whether the finder is supplying the actual findspot of an item, and not one that is merely convenient? How many times have they caught an artefact hunter for example trying to present an object as having been found where it actually was not? One of my own first contacts with metal detectorists (more than forty years ago) involved a situation precisely of that nature which involved me in a lot of unnecessary fieldwork before the truth dawned on me that he was lying. But he's dead now and it will never be known now how many other finds which he brought to the Museum had been given false provenances.