Least the average girl in USA probably doesn't have some form of STD. I can be sure the average aussie chick has been in the sack with twenty guys before me, And no amount of protection will ease that feeling.
Actually, from my experience with US girls ... well... I've been around the "expat block" a bit during my expat time and girls from the US have a very distinct reputation for promiscuity and a certain infectability ... only rivalled by the "if they could, they would fuck your passport" girls you meet around the globe.
"We don't need a condom, I can't get pregnant tonight". Uhm, I rather use one, if you don't mind ...
Now I'm terribly curious what series of events brought you to this conclusion...
Well, I like to talk with girls and I want girls where I feel challenged and that have character. But that hardly fits for "nerdy girls". Those I met where more clinging to some kind of "social niche" where they tried to attract the attention of the average male by being "different". And they act really immature and boring. (imo).
Nah, I like girls that are interested in "girls stuff". Politics, law, social problems, art, music. That stuff. Nerdy girls are just plain boring for the most part. I'm nerdy enough for two, I don't want to talk to myself with boobs all evening. (Actually ... )
I did work in a comic book store during my late teens, early twenties, so I had my picks. A slight, very, very slight "nerdy streack" might be accepted based on hotness.