What is the test for a mortgage lender's ability to assess the value of a mortgage security under mortgage law?

As noted in Law Society of Upper Canada v. Abbott:[11] Absent genuine deposits paid by the purchasers and proper credits, a purported purchase price is not the real purchase price as the vendor receives less than the purported price. The true purchase price is a material fact in the lending decision because it is relevant to the assessment of fair market value of the purchased property and thus to the value of the mortgage security. Whether the purchaser is committed to the transaction by having “skin in the game” is also relevant to the lending decision. … … most importantly, the absence of genuine deposits and genuine credits suggests that the transactions themselves may not be genuine, that the parties are not at arms’ length and that the true point of the transaction is to obtain money from the mortgage lender rather than to actually purchase property. Whether or not money is actually lost, false deposits and false credits are a fraud on the mortgage lender because the mortgage lender puts money at risk (as the lender does in any mortgage loan) based on a deception as to material facts of the transaction. [emphasis added]