How Many 'Planted' Finds in British Fields?

 

If you look at metal detectorists' forums (and why not?), you can quite often come across mentions of commercial detecting enablers (rally organizers, detecting holiday hosts)  "seeding" the fields where an activity is to take place. Maybe they've found a convenient and agreeable place to hold their events and may not want to move. But after a crowd of blokes have "done" the same half-a-dozen fields, the finds begin to dry up, so ("it is said")  some of these blokes go out and buy a few job lots of assorted bits from ebay, or scrounge from their mates' scrap buckets and scatter the bits in the field just before harrowing so event participants will see and report that more old-looking  bits of metal and partifacts keep coming up from "Scraggy Joe's Digs" or wherever. There are FLOs (no names) who simply refuse to touch material from certain "metal detecting holidays" (no names) digs. They know that none of it can be guaranteed to actually be from the field where they were found. 

I have a feeling that this practice was more prevalent in the past than it is today. One reason is that metal detectors were less sensitive than they are (reputed to be) today, so there had to be more metal in the soil to produce the impression among participants that a "dig" was more productive.  

The problem is, if "Scraggy Joe's" customers did not find all the added bits, then they lay in the soil for ever - or until they are found by a detectorist or fieldwalking archaeologist decades later, long after Scraggy Joe has moved on to other pastures and memories of his activities fade. And some of those found by detectorists will be taken to the PAS, who now employ a fresh, young, eager new FLO to replace the one that came after the one that had had dealings with Scraggy Joe.  And a farmer who barely knew the bloke he bought the land from and certainly does not know whether he let detectorists on it or not.

It seems to me that some of these potentially planted finds (alongside old collector's losses) are now turning up in the PAS database and for some reason (why?) are not being recognised by FLOs for what they actually are. There are objects that are clearly modern fakes that have been handed in and a FLO has naively treated them as genuine artefacts (some are types that are very well known to collectors). There are objects that have a well-known distribution well away from the British Isles and the area between this and England is a blank space. They are recorded by insular-minded FLOs who do not know their European artefacts. 

I was wondering if there was some way we could come up with an algorithm suggesting the likelihood that a field in a certain region could have planted artefacts. The number of metal detecting clubs and groups organizing "pay to dig" events in the past and their density on the ground (the more clubs the more they have to make the effort to be competitive). What other factors need to be taken into account to make FLOs more aware that a in British metal detecting, a "findspot" need not be what they seem to automatically assume it is?