Credit card was charged a $50 cleaning fee subsequent to returning the car for "excessive sand". The car was inspected when I returned it and no mention of dirt or any problem. I know the car was not excessively dirty. According to the contract they can get away with this and you have no recourse but to sue them. Feel like I was ripped off.
The car was quite scuffed up with 68K miles and needed shocks so didn't feel particularly safe when floating down the highway.