Regarding the Justicar:

SPOILER!!:
You have the option to kill her and recruit her daughter in her place who is very much interested in sleeping with you. Of course, you'd die if you did, Ninja Scroll style, but the thought is there.
.
In case you didn't know.

And as for Tali, she loads herself up with antibiotics and other stuff before getting it on with Shepherd. It's just a tease too because she takes off her helmet (actually, Shepherd does), but they pull Pulp Fiction on you and you never get to see her face.

Though some early concept art has her looking not so unhuman (but who knows about hair, or possibly lack thereof).