(it's a family filling station),all quite thoroughly dirty. (12-13)
The fact that it's family run and it's dirty says something about the family indirectly, too: they're probably pretty dirty. So is the speaker judging them just as much as she's judging their workplace? Can we even separate the two? They do live there, after all.
It has a cement porch (15)
Not exactly a glam look. And here's the first hint that this family doesn't just work at the station—they call it home. So the question is, does this make the speaker more friendly and sympathetic to them? Or is she just plain horrified that these folks are willing to live in a grease trap?
a set of crush and grease-impregnated wickerwork; (17-18)
So wicker is definitely a little cuter than the cement porch the furniture sits on, but if it's grease-impregnated, its cute factor is seriously diminished.