what you are contemplating is fraud
Its a very big leap from saying what I *can* do to think that I am contemplating it. I think that I have a far better idea of what the ATO targets than a guy who has a drinking buddy that works for the ATO, even if it is Michael Carmody himself.
Every 6 months the ATO issues a document called a "Compliance Program". It is distributed to all registered Tax Agents. It contains information on what areas of the law (which does after all stretch over for weighty volumes) the ATO will be targetting in the forth coming period. The ATO does not generally concern itself with whether or not income comes from illegal sources, although it may refer matters to the Federal Police if warranted. However, this is not a federal crime, if it is a crime at all (which is doubtful) and they do not generally exchange information with state government agencies.
You inferring this is in some way laundering is so off base it is laughable. Money Laundering is the process of concealing the true source of illegal funds. For starters funds received this way would hardly be illegal and they are not disclosed in any other way that that in which they are received. Its a bit hard to lie when its on your merchant statement as being received. But then its also hard for the ATO to disallow something for which a cheque has been drawn, the encashment appears on a bank statement for it, it is traceable to a third party account, and it is properly dislosed in the trust ledger. What exactly is being laundered?
I take an amount into my trust account. I take it via credit card receipt. I have disclosed to the client that there will be a 1% fee to offset my credit card transaction fees, and I deduct said fee and record it in the trust ledger along with the receipt of money. At some future time my client requests a refund of the amounts held in trust for the client, so I issue the client with a cheque drawn on the trust account. I have no agreement with my credit card provider that I am not allowed to make a refund in this manner if the funds were received by way of credit card payment. As such I have breached no agreement and broken no laws. In fact I have properly operated my trust account. As a result of this transaction the client earns a benefit with a third party which it has been established in Payne's case is not taxable income. There is insufficient nexus with income earning activities for this to become attributable income as no service was in fact rendered.
Purely from a legal perspective, I see nothing wrong with it. On the question of ethics - that is another question entirely. Being able to do something does not necessarily mean that you should.