I took a class on learning (I know that sounds weird. It was one of those "How to help your child navigate their academic career" things...) they said you really only retain 10% of what you hear, and that's if you're really paying attention. If you split your attention by doing something else (driving, cleaning, etc), it's even lower. I can only listen to audio books that I have a low level of investment in because I miss so much of what's going on. I prefer non- fiction, and a lot of the time I'll listen to it twice so I can make sure I get more info. So don't worry about not being able to remember what you heard. You can probably train yourself to focus on it better, but like you said, they might not be for you.

I'm thinking they meant that the actual cheeseburger represents pain. Like the character associates it with hurt. If this person was starving, but the guy bought her a cheeseburger with strings attached (like he expects her to do something she doesn't want to in order for him to give it to her) then it's "the cheeseburger of pain".