Lord Atrios says "Not all things are unknowable" about how bad the toxic/troubled/misunderstood Assets are. There is actual documentation for the subprime loans in the form of "LOAN TAPES" (caps in the original):

But the way to determine whether Geithner's and the banks' stated view of the toxic assets has any merit, is to demand an INDEPENDENT EXAMINATION OF THE LOAN TAPES, particularly looking to establish the prevalence of missing documents, misrepresentation, and fraud.

I'm not an economist but I think the point is: the Geithner plan aims to use trillions of taxpayer $ to prop up the price for toxic assets so the investment banks can sell them off.

The stated reason: the actual value of the toxic assets is supposedly "unknowable". The more likely explanation is that the investment banks don't want to know, and more importantly they don't want anybody else (taxpayers, investors) to know how crappy their toxic assets are.

But there are tapes (via Digby):

It is impossible to detect fraud without reviewing a sample of the loan files. Paper loan files are bulky, so they are photographed and the images are stored on computer tapes. Unfortunately, "most investors" (the large commercial and investment banks that purchased nonprime loans and pooled them to create financial derivatives) did not review the loan files before purchasing nonprime loans and did not even require the lender to provide loan tapes.

So, if there were an actual review of subprime mortgage "loan tapes" we would find out:

- the real probability that the subprime mortgage assets the US is buying really went mostly to "homeless meth addict[s]" who will never ever pay the loans back.

- how many people at large and small financial and mortgage institutions should go to jail because of fraud or deliberate negligence.

Odds of this happening?