I was thinking it would be kind of up to the next passenger. If they are ready to get in the car/Uber, and notice it's extremely dirty, or god-forbid someone puked in their recently, maybe they have something on the app or in the car that says "Report car for service inspection/cleaning" and "request another ride".
Uber already charges a cleaning fee of $40-150 at the driver's discretion. There's margin there for the cleaning cost, opportunity cost of the vehicle time, and a credit to the reporter for the trouble of seeing vomit and waiting for the next car.
