I'm a woman but I have no fucking idea what she's going on about.

I'm pretty confident that I have never smeared faeces onto my own labia. Like you, I don't even understand how that would happen. That should be the kind of mistake you make only once 😐

It is. Putting a hand or hands on another person without their consent is assault in the eyes of the law. The only time it's okay is if you're touching them to attempt to save them (CPR isn't assault even if you don't have prior consent, for obvious reasons) and of course when in a crowd for example, your hand brushing someone's elbow isn't enough to be classed as assault as it is more than likely an accidental act.