I have been charged a "vehicle cleaning fee" for a rental car return. The rental car office "believes the car requires more cleaning than usual". I have frequently returned cars much more dirty than this. Are there any norms for how much cleaning is "usual" or is this just a fee that the office may apply more or less at will where the customer has little recourse to challenge? I've returned much dirtier cars without a cleaning fee in the past.
The car return itself was by drop off, and I only found out about the reason for the extra charge several weeks later with the help of a customer service representative at booking.com (the rental car office did not inform me directly).
There was dirt on the outside due to driving on dirt roads, and dirt/sand/grit on the inside coming from shoes. The car was certainly not clean, but I have always returned rental cars in such a state and never run into problems. We did not smoke as we are non-smokers (for smoking I would expect a much larger fee than the €30+tax+meta-fees we were charged).
In case it matters, this was a "Keddy by Europcar" rental in Granada, Spain, booked through booking.com.