No matter how precise they try to make UAD categories, many houses are a blend of quality - some aspects may be Q5 and other Q4 in one dwelling
So which is dominant ? There is no way UAD can possibly address each property- which is why. Imo, if an appraiser is not trying to be misleading, whether they call a borderline house Q5 or Q 4 , it should not affect the credibility of the appraisal, - if you can think of a way to fool proof categorize every finsih, upgrade and defect, of every single diverse dwelling out there, would look forward to seeing it!