Some nasty things have been said about Gradient Analytics, even resulting an SEC investigation of the firm that was dropped in short order.

But as Herb Greenberg points out in his latest column (subscription required), the research firm has about as stellar a track record as you will find, having been among the first to raise questions about accounting at Krispy Kreme Doughuts (NASDAQ: KKD), Children's Place (NASDAQ: PLCE), and Biovail (NYSE: BVF).

Now, in a report available free on the firm's website (a must-read if you are even thinking about buying financials), Gradient wonders about the accounting at Washington Mutual (NYSE: WM), Citigroup (NYSE: C), Wachovia (NYSE: WB), Wells Fargo (NYSE: WFC) and, my personal (least) favorite, Countrywide Financial (NYSE: CFC).

According to Gradient's report, the financial statements of these firms raise serious questions with respect losses being hidden on assets that are being held to maturity (essentially failing to take appropriate writedowns), shifting loans into "assets held for maturity" to avoid taking writedowns, the use of "not necessarily fair market values," off-balance sheet arrangements, and the concealing of the "after-effects of aggressive gain-on-sale accounting."

Gradient currently sees Washington Mutual as the greatest risk in the group, followed by Countrywide Financial.

In past posts (here and here, among others), I've written about what I see as the major risk that investors face as they dive into financials in search of value: the financial statements are only as valuable as they are reliable, and there are a lot of questions about their reliability. You cannot be a value investor based on inaccurate or deceptive 10-Ks and 10-Qs.

There could be opportunity here, but the likely presence of accounting shenanigans adds a "known unknown" that cannot be cast aside.