Mike,
If addressing at CNAREA the following might not have any use--but if clients are following some form of standardization--in the US Fannie Mae appearing to be the source of compliance-check out Selling Guide B4-1.4-16
The appraiser is responsible for determining which comparables are most appropriate for the assignment. Fannie Mae expects the appraiser to account for all factors that affect value when completing the analysis. For example, if the appraiser believes a foreclosure sale or a short sale is an appropriate comparable, then the appraiser must identify and consider any differences from the subject property, such as the condition of the property and whether any stigma has been associated with it. The appraiser cannot assume it is equal to the subject property. A foreclosure or short sale property may be in worse condition when compared to the subject property, especially if the subject property is new construction or was recently renovated. The appraiser must conduct the proper research in order to complete the assignment and provide an accurate opinion of market value.
As for adjusting subjecct concessions--never do--but I have noticed that in certain areas of the country the subject concessions were the basis of an adjustment to the comps--which is totally incorrect--don't know what CE they were taking.
Monica L. Trotter, IFA