Interesting. I've been doing it by "family" just for flavour, but might try and get more fun. I only have one girl interested in threesomes, and that is not enough: I sure as hell am not going to invite Ansel :D
Maybe the dorms are a free for all. I never saw anything down in the basement. But I am running a pretty decent house with low corruption values.
Another topic. I would assume that Totalube would be on by default. Adrienne Keller came to my house at 17. She then turned 18 and some time later we had some fun together and she got pregnant. I went to check at totalube was off (never did check it, so IDK). So now I will be having 3 little ones. Even though the wiki says (I think) there is a 30% chance of pregnancy and we should fill the sperm meter, I got 3 girls pregnant on the first go. Could I be extra lucky or maybe a bug? I don't have the big load perk.