Having been involved in theory training decades ago, I shake my head as, at the end of the day, it's probably less effort to do the hard yards, pass the thing on one's own merits, than to run the stress and wasted time of being underhand.
More to the point, the real aim is not so much to pass the exam .. that's just a nuisance sideline matter .. as to end up with some potentially useful knowledge tucked away in the brain archives.
A simulator will quickly sort out the pretenders from the real thing.
The kids who don't have any substantial background (ie slept through lectures and fudged the exam) get found out pretty quickly when they can't match the pace required in training ..
As an old airline ground school colleague observed over a beer .. "At XXX, we aren't too worried about the pilot exams and I'll keep walking past suggesting that Bloggs revisit Question Y again .. until he passes. Our job is to get them exposed to the stuff ... if they then aren't up to the grade, the sim endorsement finds them out and is the end of it for them".
Mind you, there is an old tale about Dusty (God's right hand man) who, on the DC9 ground school (as I recall the tale) was given a "special" Dusty exam paper. After everyone else had finished and gone to the pub, Dusty was still tearing his hair out trying to figure the paper ... eventually the boys let on .. I didn't hear the exact response but I have no doubt that it may have been a tad blistering ...