If customers thought they were being misled or missold products, they would either sue or complain to the SEC - something which unhappy customers routinely show a willingness to do.
Been there, done that, got the t-shirt.
Banks Bundled Bad Debt, Bet Against It and Won - NYTimes.com
He mentioned Abacus in the letter. Maybe you missed that sentence?
SEC Charges Goldman Sachs With Fraud in Structuring and Marketing of CDO Tied to Subprime Mortgages; 2010-59; April 16, 2010
[FONT=Verdana,Arial,Helvetica]According to the SEC's complaint, filed in U.S. District Court for the Southern District of New York, the marketing materials for the CDO known as ABACUS 2007-AC1[/FONT]