Bava Metzia 57: The Temple Won't Take Advantage (Because It's Allowed)

When is the capacity to take advantage of another not relevant? And if there's no risk of exploitation, is there any recourse to cancel the transaction for other reasons? Note the exceptions of consecrated property (hekdesh) and land... Also, what if transactions or loans are made in conjunction with consecrated property? The Temple has some flexibility with fluctuations in the costs of things - without it being exploitative.