Really, the disease factor shouldn't be the reason to say no. Yes, yes I know that no one wants a disease, so one must be careful. However, what's the difference between the first date and the third date. Let's say you're dating a girl and she does have something. Now, you're on your third date and she's thinking Boy, I'd really like some cock and, if I'm lucky, some good head. Do you really think she's going to bust out with "Oh, by the way, I have herpes, genital warts and the clap." No, she's not. It's a gamble, period. I don't even think most girls, or men, are honest about their sexual past no matter how many dates you've been on.