Being a paying parent myself, and having been in the situation where the kids have often either going without, going with too little, or my ex hounding me for MORE than my share... I admit that I have wished she could have to account for how her money is spent. THE ONLY REASON BEING that she never seems to have enough... or she always wants more... or she wants me to pay for EVERYTHING...
I can guarantee that if my kids dressed better at their moms (not style- I'm talking clothes that actually FIT and are in decent condition) ate better (a vegetable here and there wouldn't kill them at her house) and if my ex didn't always act like the 41% of my income was just so pathetic, then I would never have a reason to question where the money was spent.
Unfortunately, I have heard that phrase too many times... that as long as they have clothes on their back... food in their tummy's... and a place to live, that it doesn't matter if the clotes are too small, their dinner is a Pop Tart and a diet coke, and the neighborhood is ridden with crime. Which is really, really sad.
But no, the courts can't be expected to micromanage how the receiving parent spends the other parents money. That's where they are expecting the receiving parent to be responsible and use that money wisely FOR THE KIDS.