"I wonder if U.S. soldiers were overpaid during WWII. I kinda doubt it, but maybe so"

I always thought the "overpaid, over-sexed and over here" thing was a British saying originally! Who knows but it was certainly known and used here too. I suppose it depends on what is meant by over-paid. I think the idea was that they were over-paid in comparison to the British soldiers. Over-sexed because the British girls had their heads turned by these exotic foreigners coming in.