It is believed payments to a number of players run up to $250,000 and were never properly registered as third-party player agreements.
"I know cash sounds terrible, and that's something I won't go there with that, but the arrangement was for him to make a payment to Paul, do the sponsorship and make the third-party payment,'' Cullen said.
"Now whether he paid that by - and I don't want to sound flippant - by cash, by cheque, by jars of vegemite, whatever, he made the payment.
"But the problem is more the documentation of that from a salary cap point of view, it wasn't formalised the way it should've been.''
Accusation were also made that Flanagan operated a high performance unit bank account off the club's books, despite the previous board ordering it be shut down.
Cullen was not aware of the account and asked if it was concerning he said: "definitely".
"You just don't do things that way, no.
"Every dollar that comes into the club, and therefore every dollar that goes out of the club, should going through the club's central account and be recorded and accounted for.''
Dozens of NRL stars have been issued with interview notices by ASADA, including 14 Cronulla players headed by Gallen, John Morris, Ben Pomeroy, Wade Graham and Ben Ross.
Cullen, says key staff members at the Sharks failed to ask crucial questions about the legitimacy and safety of the supplements regime introduced by biochemist Steve Dank in 2011 and that there are no records of who paid Dank for his services.
It was revealed the pharmacist whom Dank used in 2011 has been found guilty of professional misconduct and penalised by the Pharmacy Board.
Cullen said the survival of the Sharks now rests on the club righting the wrongs of the past and ensuring they do not make the same mistakes again.
"I'm not too sure whether they've learnt their lesson or not,'' he said.
"Worst-case scenario, I fear for them and a whole lot of things about player suspension, players suing the club for loss of income, players suing the club for player welfare.
"Best-case scenario, they'll be fine. They have the commercial development to fall back on.
"Worst-case scenario, they are going to have some huge challenges.''
-AAP