I get your feeling as well of not being able to put it into words. It is seriously so tough to determine where the line is between a gold digger and a non-gold digger.
About the female doctors. It would financially make sense if they just dated another doctor but you know what I have heard from several of them. They aren't really attracted to the male doctors. They are then pulled in two different directions. They want a guy who is attractive and athletic but most of the time they aren't going to be able to make as much as a doctor busting out 14 hour days at the hospital.
I do see a lot of female doctors end up having kids a few years after being a doctor and then drop to part time. They give up their 20's and then they have the window between 30 and 40 to basically have a kid. It makes it kind of tough for them for sure.
I will say this though. The least gold digger girl I ever met was a doctor. The reason I say that is because her earnings were through the roof and she wasn't high maintenance. She never asked how much I made or anything like that and we were around each other enough for me to tell she wasn't worried about it.