Players often don't have a clue, ZG, particularly when they are lower tier players, often no more than young backpackers, coming from parts of Asia and South America, and not English speaking. They may have played futsall, or the equivalent of pub football, Sunday league stuff, and have no idea about the game's superstructures.
And to request a clearance you need to nominate a club/association to get clearance from.
On the other hand I must say it's been fascinating to see the issue of Frederico Marquez - good enough to start for Canterbury in the national league despite never played affiliated football before 2012-13 if clearances can be believed. :-)
One of the funniest instances, in reverse, was the case of Steven old (Manawatu) back 8-9 years ago.... His new club diligently sought clearance from his New York university St Johns - received it, then played him... only to belatedly find the university operated outside of Fifa statutes and he registration actually still resided with his former Palmie club from years earlier. Ooops. But that one was brushed under the rug.
It's not always black and white with these things.
But just out of interest, ZG, I would be interested to hear the way you see it with the case of Alejandro Ferrari - one of the players ruled ineligible after the Papakura fishing expedition - who was signed from Tauranga City United, where he had previously played northern league? Should there be a statute of limitations on these things?