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The speaker in "Filling Station" would appear to be a very observant individual whose preferences are for a standard of cleanliness considerably different than is present in the surroundings being described. Both the father and the sons in this family-run business are in need of a good bath and fresh laundry, in the opinion of the narrator. "Father wears a dirty, oil-soaked monkey suit...and several quick and saucy and greasy sons assist him...all quite thoroughly dirty."
Looking further, the narrator makes note of the furnishings, the accessories, the attempts at refinement in the midst of the dirt and grease. The impression that the narrator is female comes out in the concern about the idea that the family lives in this setting. She can't quite believe the care someone devoted to creating the handwork of the "big dim doily...(Embroidered in daisy stitch with marguerites, I think, and heavy with gray crochet.)" She's mystified by the presence of "a big hirsute begonia," but perhaps also reassured by the unseen care someone is giving this place and the dirty men who live there.
Even though she's never physically present in the poem, the speaker is pleased to think that another woman is present and "loves (them) all" - the residents and the customers of the filling station. After starting out rather critically in reaction to the dirtiness and greasiness, the narrator concludes that the place looks like an oasis of care beside the road.