I get the impression that it all depends on which ECO and Immigration Officer you get
No, it does NOT.
A visitor's visa & a fiancee visa are two different things.
In the case of a visitor's visa, you must have sufficient funds to pay for your upkeep (hotels, food, travel etc), or have proof of access to sufficient funds.
In the case of a fiance/marriage visa, your (future) husband has already committed to paying for your upkeep. This was part of the application process.
... so, a fiancee can legitimately arrive here with not a brass farthing in her pocket.