There is one simple rule; Look for contradictions between financial analysis and market behavior shown on the chart. When there is a contradiction always believe the chart. Investors who applied this rule to General Motors, Citibank and Bank of America all avoided substantial losses in 2008. Analysts and company reports were defensively bullish, blaming irrational behavior for the initial price falls. Market behavior shown by the price charts and simple technical analysis showed the market did not believe the financial analysts.
Technical indicators are the only true objective gauge of market psychology and money flows. That doesn't mean investors get every call right. Understanding charts and price activity is part science and part art. But the investment discipline of technical analysis gives a significant advantage over analysis methods that rely on the unfailing honesty of company financial reports.
Subprime products were not traded on the open transparent market so there was no method to independently assess the information provided by the promoters of these products. The rating agencies were unable to overcome the inherent conflict of interest in their business model.
Financial product developers, such as Goldman Sachs pay a fee to the rating agencies to "independently" provide an investing rating for their financial products. Conflicts of interest are inevitable and unavoidable. The solution for truly independent rating of investment products is complex and difficult.
Transparency in all financial market trading is essential. Transparency provides the additional layer of protection against fraud because investors can see the behavior of the market and identify contradictions. The methods are cheap and available to anybody who wishes to use them.