And no, the definition of typically motivated is not a moving scale...same with undue stimulus.
__________________
Am not sure what you mean by a moving scale...however typically motivated and undue stimulus are defined by the forces impacting the market.
The very term, MARKET VALUE, encompasses the word "market", and markets are always changing, never static.
Thus, the definition of MV relates back to the market, and every analysis of markets recognizes that they are always changing ( captured in a moement of time, the effective appraisal date) . Part of the changing nature of markets are the large number of REO and short sales present now. In a few years, that inventory will be gone, and other sales types or trends will dominate the market.
If you insist on using a static or fixed definition of "undue stimulus", where do you get it from? FIRREA does not provide one. To the best of my knowledge there is no gold standard, precise definition in USPAP either. And the same goes for typically motivated. Though the term typically motivated is often used, where is the official, static, standard, unmoving definition? You personally define it often in your posts as the traditional sale or traditional buyer, yet the term traditional sale or traditional buyer does not appear in FIRREA or USPAP.
I had a very great USPAP instructor tell our class that USPAP left definitions of key words delberately broad, because these key words are always being shaped by changing markets, and thus a precise definition could never encompass the fact of that dynamic.