None of your business really what she is spending the child support money on.... Who are you to say that the $30 she spent on her nail (just a example) comes from the child support or from her money? How can you differ the two?

Are the kids homed, fed, clothed and schooled? If so the child support is being used appropriately.

And for what it's worth I get not a cent from my ex for 3 children and if he did pay there is no way in hell I would let him ask or dictate how I spend it.