The kerfuffle on FT suggests they were pretty attractive

No idea how good they were relative to legitimate fares offered to the public. That's why I asked the question.

There've been a number of claims they could easily have been confused with legitimate fares fully intended for retail sale to the public. But examples have been vague and unsubstantiated. The only ones I have any experience of were the (now ancient) Tripoli fares, but these were hardly straightforward....