If you have time and interest, Jonathan Miller has an well written article about the effect HVCC and AMCs have had on appraisers and appraisal quality, and the use of distressed sales in reports.

Here: "Appraisers and Foreclosure Sales Bring Havoc to Housing Markets"

In general, I find his blog, "Matrix," informative, well considered and well written.

He has a section devoted to appraisers and appraisal issues, if you are not interested in the NY real estate scene.