The scam and my idea ARE different, but the same principle allows both to be accomplished. Funds are made available from checks well before money is collected.

The scam and my idea ARE different, but the same principle allows both to be accomplished. Funds are made available from checks well before money is collected. To someone unaware of the system, they might assume the check was good because the money was cleared into their account. This is what would trick ExchB into granting you BTC without the guarantee that they were paid.