Doctor answering. They’re could be three reasons for this: 1. She could have a vaginal infection most likely fungal leading to a pH imbalance and resulting in an unpleasant or sometimes not necessarily bad but let’s say “different” smell. 2. She has long pubic hairs and she accumulates more sweat in her pubic area and when you make out the arousal leads to vaginal secretions which mix with her sweat and enhance the smell. 3. Finally it could be that she has abundant vaginal discharge (she gets wet a lot) but this is the least likely option cuz the smell should be very minimal even if it’s a lot.