That's not only disgusting, it's illegal. She could be arrested, and the restaurant could be shut down (at least in SC). Owners/managers will not put up with that.
I found a stray hair in my food once, and the manager cancelled our bill.
I have very short salt-and-pepper hair, as does TCS, and it was a long blonde hair, so I know it wasn't ours.
However, at a Cracker Barrel (which we only go to if a group invites us; it's not our choice), it was a different story. TCS found the dispenser parts to the drink machine at the bottom of his drink glass. The only thing he got was a fresh drink (fresh, not free).
BTW,
why did the server spit in your food?