148 Should We Really Be Making Adjustments?

An appraiser inspects the subject.  An appraiser chooses comparables.  An appraiser makes adjustments.  An appraiser reconciles the report.  Right?  What if an appraiser did not make adjustments?  Would it change the outcome?  How accurate would appraisals be without the adjustments?  Can you support your adjustments?  I mean REALLY support your adjustments?