I mention no car wash every time I go to dealership for any service and after so many years of relationship with the dealership, they make no car wash as the default for my car. And I always bring a clean and washed car to them for every service to reduce swirls done by whoever works on my car. I think a dealership certainly welcome a clean car before the service for a customer who has high standard of car care. It is almost impossible not to induce some kind of minor swirls and hairline scratches to a dirty car during a service.
2014 IS350 AWD non F Sport, Xpel Ultimate
2011 RX350 AWD, Ventureshield Ultra