In Blaise's circles there was no sugar coating. When someone wanted to know something they asked outright. Of course, they could be cunning and a bit deceitful but that didn't mean that when seeking definitive information they weren't cut throat as well. So for him to cut right to the chase rather than trying to sweet talk his way into an answer was actually quite a compliment. It was a show of acceptance that most outside his purview were rarely treated to. It was a courtesy he wouldn't have given her if any of his cohorts had been around.
He listened to her make her case and gave a slightly puzzled look. "First off you aren't a professional. Second, what do grown men want with a school girl?" It was not meant to be a slam toward her reputation, but he couldn't help but wonder what sort of man would go after a girl still in Hogwarts. True, he was of age, but he was also still a student. Once he graduated he had no designs on keeping tabs on any of the girls that would have to return to the castle in the fall.