Clearly, once the scam was recognized, customs officers around the world would have had their internal alarm bells set ringing anytime some traveler presented a Nauruan passport. At that point, it would have been almost better to have no travel documents at all than to have one from Nauru.
Traveller: Sorry Officer, I have no papers.
Customs: Hmm, that's a bit awkward, you see we normally do like to see a passport or something. Perhaps you could write yourself a little note saying where you're from?
Traveller: Sorry, no pen.
Officer: Ahh I see, well, that's probably best actually, we're trying to cut out self-asserted. Now let's think about this ...
Officer: (brightly) Say, you're not from Nauru are you?
Traveller: No sir.
Customs: (pause) Welllll, I guess I can make an exception. Just this time though OK?.
Strangely, I have more trust in Nauru's passport office than I do in its national airline.