One kind of obvious thing about financial markets is that you can't just call everyone into a room and tell them, "look, guys, just be honest about the price that you would pay / receive for Thing X." This is because financial industry traders are degenerate lying scumbags. No, wait, that's not right. This is because if everyone just told each other their reserve prices then it would be really hard for them to make any money trading and so we, like, wouldn't have a financial system. So you have things like anonymous execution on stock exchanges and dark pools and, um, lying scumbag traders. And that allows you to have profitable trading. Of course you have to put some limits on the lying scumbaggery: you can't tell people you're investing their money while really blowing it on hookers, and I guess now you can't sell someone synthetic CDOs without telling them who was on the other side. But a little fudging around the edges about the price you're willing to pay or receive - or the price you could pay or receive elsewhere - is kind of at the heart of what trading is. So in a sense the amazing thing about the Libor scandal is that people are amazed by it. A quick recap:

Case closed, end of story.

Let's talk about "theoretical" pay.