A few thoughts.
1) I think calling her a hooker is incorrect as Barber claims no money exchanged hands.
2) Does it seem a little suspicious to anyone that he was worried about having someone who is drug free?
Why if you are trying to have sex with a random stranger would you care if she is drug free. Presumably, you are going to wear protection so why would you care if she was on drugs? Particularly since he said he didn't know you can get cocaine from kissing someone.
3) Is it common knowledge that you can get cocaine from kissing someone?
1) Calling her a hooker is absolutely correct. "M" is her pimp. His actions were those of a pimp. Shawn either lied when he said no money exchanged hands, or he exchanged something that wasn't cash. Pimps don't work for free.
3) No, but apparently it is scientifically proven to be possible, and will be much more common knowledge now.