I'd consider complaints about cleanliness a good thing.
Many mechanics curse a dirty undercarriage, but never tell the customer. It's not only an inconvenient place to work; jobs can take longer to complete, sometimes, as well as require cleanup of both the problem area (and as a result, the shop floor) and that cost must be passed on to the customer, which they won't appreciate.
More importantly, however, dirty parts hide issues, and can even help cause issues. Cleaning is a maintenance procedure, and a good mechanic will advise a customer on maintenance that might have been neglected.
Cheers,
Kennith