When you're white in places like Asia or South America you are presumed to have money regardless of whether you do or not.
Although I rarely found it hard to figure which girls were just after your money. In fact it was usually as simple as finding out her career/educational background. If she was in college or had a decent career she'd usually at least offer to pay the taxi. Often offering to pay half the dinner as well.
Maybe it's different in Asia but most gold diggers in S. America were simply upfront about their intentions, in other words they were prostitutes. There's very little shame in being a prostitute in S. America, you'd often see old 40 - 50 year old western men going around with 20 year old hotties who would genuinely act like their girlfriend and often did seem to actually be enjoying themselves.