It certainly depends on the beneficiary and geography, but in general the stated opening bid on an auction notice (NTS in CA) is the unpaid balance including late fees, plus costs of foreclosure and any advances to priority liens.
That said, I monitor much of the TS activity in San Diego and Orange County and I have seen a definite increase in trustee’s lowering the opening bid amount below this at the bene’s request. In some cases that’s translating into a rare sale to a third party at the courthouse steps.
This is one of the key reasons why auction pros, when they’re active, do not ignore properties that might not make sense at the NTS amount.