A lot of shops still stock whatever bulk fresheners come cheapest at the auto parts supply store: assorted scents, minimal packaging, the kind of thing that costs pennies and looks like it. For a basic wash, that might be perfectly fine. For a premium detail running $200 to $500, it is actively working against everything else you did that day.
The math on switching is not complicated. Bulk bin fresheners run cheap for a reason: minimal formulation, synthetic single note fragrance, packaging that looks exactly like what it is. A cosmetic-grade, perfumer-crafted alternative costs more per unit, but on a premium detail, the difference is a rounding error relative to the total price of the service, while the perceived quality gap between the two is enormous.
There is also a consistency problem with the bulk bin approach specifically. Assorted scents mean every finished car smells slightly different, which undercuts any attempt at building a recognizable signature standard tied to your shop. A client who books you twice should get a consistent experience both times, not a coin flip on which random scent was left in the bin that week.
Clients evaluating a premium detail are not just looking at the paint. They are absorbing the entire experience, and the finishing scent is part of that evaluation whether they consciously notice it or not. A bulk bin freshener tells them the finishing details did not get the same attention as everything else. That is not the note you want a $300 job to end on.