I'd like to know if "foul" has the same meaning in these excerpts from The Great Gatsby by F. Scott Fitzgerald:
-1) (chapter 1) No—Gatsby turned out all right at the end; it is what preyed on Gatsby, what foul dust floated in the wake of his dreams that temporarily closed out my interest in the abortive sorrows and short-winded elations of men.
-2) (chapter 2) The valley of ashes is bounded on one side by a small foul river, and when the drawbridge is up to let barges through, the passengers on waiting trains can stare at the dismal scene for as long as half an hour.
In the two above excerpts, the word foul does have the same literal definition [offensive to the senses]; however in the first excerpt the word is used metaphorically, only, while in the second excerpt it is used literally with the additional connotation suggesting the symbolic meaning.
(1) Taken from his prefatory paragraphs in Chapter One, Nick's observation that the "foul dust in the wake of [Gatsby's] dreams" is what turned him against the "short-elations of men," such as those of the East coast, implies that Nick has found the behavior of the socially elite such as Daisy and Tom Buchanan reprehensible because of its offensiveness to his sense of morality. For, in Chapter Nine, Nick comments on the foulness/"the foul dust" of the Buchanans,
...were careless people...--they smashed up things and creatures and then retreated back into their money or their vast carelessness or whatever it was that kept them together, and let other people clean up the mess they had made...
(2) In the description of the river in the Valley of Ashes, the river is offensive to the physical senses because of the waste and contaminants that have been thrown into it. Additionally, the foul appearance of the river is symbolic of the waste and corruption connected to the industrialization of New York as well as the materialism of the Jazz Age.