I'm pretty sure it's mentioned somewhere that Blue Moon was one of several properties Maddie maintained as tax losses. In other words, not that I know much about breaking federal law, but they were deliberately supposed to lose money so that she could write them off, thereby saving on the actual grand total of taxes owed each year.
So...that creates an interesting 'partner in crime' dilemma, literally! From Maddie's side, because she knows things are rigged this way to help her get around the law; and from David's side because I think he says words to the effect that, he knows that's why she's doing it. He says something like, the agency only lost money because she wanted it to, that's the way she wanted it run, etc. Didn't check my DVD but I think that's the gist of it.
This is kind of a weird dichotomy--in a way, they're working together before they ever meet! ;D But they're also doing something that's more than a little shady. A sad effect is that since Maddie was robbed, she doesn't even have enough money left for this to have worked to her advantage. She didn't make a profit. See? Crime doesn't pay.