The Doctor's eyes widened when Rose said she was a cooch dancer. "What?" he asked. He tried not to think too hard about that. "Yes, they must have thought so," he said, in regard to Jack's comment. He wasn't surprised that Jack knew some of the other dancers.
The Doctor glanced at Jack. "What do they make you do?" he asked. He hoped that Jack didn't have to endure suffering as part of his job.