What should I do if I get the hotel sheets dirty because of sweating?

Washing is a normal obligation of the hotel, and guests don't need compensation.

From the point of view of contract equivalence, customers have the obligation to take care of the facilities and supplies provided by the hotel. If the customer causes abnormal damage to the hotel facilities and brings extra workload to the hotel, then as a service provider, he can negotiate with the customer and charge a reasonable fee.