I mentioned it, because I think there is some credence to the stereotype. I noticed this when I taught at a gym. There were certain women who looked fit, in shape, and were often quite thin. Yet, when they came to my class, they never sweat, and often never had the endurance to make it through my class. This was during the time I was very thin, from just too much exercise, so I really noticed it. I still sweat buckets then, and I always wondered how these women managed to look like they never lifted a finger when working out.
I used to have "names" for all the types I would see when I taught and this was definitely one of the types.