The appraiser performs the analysis inclusive of the comparisons they make. How they obtain the information they analyze is strictly subordinate to the act of performing that analysis.
If you use someone else's analysis in lieu of your own then say it that way. If you perform your own analysis then say it that way. The only way it gets more complicated than that is when you try to attribute to these inspectors the actions that the appraiser is actually doing themselves. Or vice versa.
IRL you can do almost any SOW so long as your users agree that its reasonable for that use, and as long as you do what you say and say what you do.
Appraiser didn't physically inspect. Appraiser did analyze the information from the various data sources at hand, including the info in the inspection report. The appraiser assumes the responsibility for the opinions they developed as a result of their research and analyses. In lieu of information to the contrary the appraiser cannot accept responsibility for the factual accuracy of information provided by any of these other data sources; however the appraiser does assert they are acting "to the best of their knowledge and belief".
It's exactly the same rationale appraisers use in disclosing the limitations that go with using any outside data source. We believe it to be reliable and (when it's applicable) aren't aware of any reason why we should question that reliability. We have reason to make these assumptions and the client and intended users have agreed with this SOW. THAT decision being their own responsibility. As for the off label users, they're on their own - they should get their own appraisals specific to their usage if they want one. Or not - their choice and their responsibility.
