Do you take a girl seriously if she sleeps with you on the first date?

There are definitely men who would judge, but in this case it's far more common for women to judge. When a woman talks to a man, he's likely to tell her he judges harshly so the girl will shut up. Therefore it's perceived that men think that way, but they know a girl would never stop nagging if a he said 'she's not a slut', so they usually just say 'yea sure, she's a slut'.