Why do I give this 1974 porn movie 7 points? Because I watched it. And I found it hilarious! Aliens, their weird spaceship, their weird helmets... my God, was that a sight. And all what these desperate alien women need is semen from the earth.
And where do they look for it? In upper Bavaria, Germany. And that is where the main fun comes from: In Europe (and more so in German-speaking countries), Bavaria is seen as a traditional and backward region. And then the actors are so helpless with the alien women. Well, there have been films about people being unable to deal with women like the "American Pie" series.
But what this film achieved is a true, funny weirdness. You constantly wonder how they came up with these crackpot ideas. But it was 1974, and looking back 35 years fills one with a kind of nostalgia. You've never seen a film like that.
And if you don't mind seeing the casual pubic hairs and breasts, watch it once. It is a comedy essentially, not a porn flick.