Exactly Tom. It would be easy to find possible errors if there weren’t genuine single QSO activations. But the figures for single QSPs aren’t massively different to two QSO activations etc. And a for example, there are 31168 activations with 4 QSOs.
So there will be some errors in those single QSO activations but I don’t think, at present, that it’s a massive number.
An activator wouldn’t be activating several different summits many miles apart withing a few minutes, so one clue might be several one-QSO activations by a single callsign within a short period of time? Another might be finding summits with single-QSO activations where there’s more than one activation on the same day? Neither would catch all cases, because sometimes folk will make just one chase, and some actual activators never upload their activations, but it might help narrow down the scope of the problem, and maybe give a hint as to how it happens? (I’d guess it’s probably folk who should be picking the “Submit Chaser/S2S Entry” from the database menu picking the first option, “Submit Activator Entry” instead, rather than uploads via CSV or ADIF. If so, the solution’s probably in the naming of the menu entries, or perhaps in swapping their order?)
… and the database queries needed to isolate them start to get just a mite more complicated too, I’d guess.
(Oops. There goes my 
coffee-break . Back to work. 
No chasing this morning…)
Your coffee break maybe over but my laptop BSODed (again) and after much mucking about and tests it’s suggesting the SSD is iffy. So I can answer this whilst IT figure out what to do next.
Yes, it is a bit chicken and egg in that you need to write a few complex queries (and debug / verify them) before you know the true scale and that my be quite some effort which when you find out there’s under 50 bad log entries you wonder if it was worthwhile!
People can enter the callsigns in the wrong fields when using the manual enter chase page, they can enter a single QSO into the activator page but I think the most common cause is getting the fields wrong in a CSV upload.
My next step is to take my list of single QSO activations and “convolve” each activation over the activations of that summit on that day. i.e. if MM0FMF enters a single QSO activation of WS-001 on 1-Jan-2020 then find any activation of WS-001 on 1-Jan-2020 and see if MM0FMF is logged as a chaser. It can’t be a valid QSO for both calls to be on same summit at same time for chase or S2S etc. And also I can discount every single QSO M1EYP activation as well as we know they will all be genuine activations.
That should give me a list of iffy single QSO activations which are candidates for auto activation to chase conversion. Just make sure I keep Tom out of the lists and it should not be too big 
This is it!
F8FEO Alain who has corrected a bad entry, confirmed that he uses only this “Menu” to enter his chasse.
So as i said before (see the picture) it should no be possible to valid an entry with the same call (if logged as f6hbi, i cannot chasse F6HBI)? Am i wrong?
Gerald