Regarding "Virgin Killer", it was indeed the record company that wanted a shocking album cover. One has to remember that in 1976, Scorpions were not the sellouts they have become, and were just about as metal as it got. With that in mind, well... controversy sells. Ask Alice Cooper, Ozzy Osbourne and Marilyn Manson. That cover was replaced in the US with a band shot.
Scorpions' 1979 "Lovedrive" did have a boob covered in gum on the european release, but the american record company would not distribute it, so it was replaced by a blue scorpion image.
It is interesting too that their album 1996 "Pure instinct" also has nudity on the cover, being humans in a zoo cage, observed by animals on the outside. The Canadian release has an unscensored cover, but I heard that the US release was, again, different, using the back inlay picture on front.