“I am currently divorced and pay child support. Can someone please explain to me what the support is supposed to go for? My ex says things like haircuts, etc. are not part of what the money goes for. Is this correct?”

Child support guidelines and calculations are designed to produce an amount of child support sufficient to cover the cost of generally providing for the child. That includes any day-to-day expense incurred while the child is in the care of the parent, including such items as haircuts.

Generally speaking, the only things not intended to be covered by child support are the cost of child care necessary to allow the parent to work or go to school, health insurance, and any uninsured medical expenses. Anything else is to be covered by the child support, as are discretionary choices made by a parent, such as ballet or karate lessons, or other extra-curricular activities. That said, a court can include other items in a court order, but these are typically extraordinary items such as tuition for necessary special education, and the like.

Recommended reading (click on the picture):
The Law And Economics Of Child Support Payments