I use the Ladies toilet all the time.
At the RSD Seminar 2004 there were fifty guys lining up for the toilet and no girls in the whole conference centre. So I took a noisy and smelly dump in there.
If there are two toilets in a restaurant, one marked male and one marked female, and the male is in Engaged, I'll use the ladies rather than wait. I'm very careful to leave the seat down.