Spotting women is difficult because they have breasts that are considered a no touch area. The correct way to spot someone is to shadow them literally following their range of motion with your body. The spotters pelvic area very close the weight lifters glutes shadowing them up and down with your forearms pressed to their upper ribs. If a client needs a spot and is a male you still have to have permission to touch them.
When spotting you squeeze inward with the forearms against the ribs and then pretty much grab the pectoral region spotting which way needed pulling up and back or up and forward . Spotting a woman is difficult but when needs to be done I believe they would welcome it. I just started training my first woman and she lifts really light weight weight that I can spot by grabbing the bar. As long as you got your reps in your good!! haha
I am sure it is a bit touchy
they all let me know what they are going to do and I have never felt "uncomfortable". I sort of look at like the doctor, not about being naked but about being helped. It does give me extra incentive to move on my own. It is difficult becaue there are really no women at the gym who lift or that I would trust to spot me.