It hasn't happened to me since I'm married! But I have 2 thoughts about that.
1. She has something so she's not afraid of contracting it and does not care about the partner she's with or,
2. We haven't been bombarded so much recently about STD's as we were in the past and I think a lot of people think the "scare" is over and can go back to enjoying a stranger's company w/out worry.