"Public trust in the appraisal profession" .
For those clients who are not actually compelled to get an appraisal, why would one of those choose to engage an appraiser instead of one of their other alternatives? Why do your clients choose to use your services instead of those of the donkey down the street who has the same license as you? If your name isn't Terrel, why do you think 2 sides of the same transaction would prefer to use an appraiser instead of the broker friend one of them knows?
And as I said before, sure, water seeks its own level. The corrupt clients prefer appraisers who will enable their schemes, the better-safe-than-sorry clients will have their preferences based on their aversion to risk. Same with the other elements of the transaction that a client can prioritize such as the fee or the turn time or the level of detail in the report or even the personal attributes of the appraiser as they go out and interact with the lender's customers.
So there are bad clients out there. No problem - leave them to the appraisers they deserve. You're looking for the low maintenance relationship that you can sustain over time. Or if not that then maybe whatever other priorities you may value.