Does "painted vapors" mean anything without a context?

The passage is from The Epiphany of Death by Clark Ashton Smith (emphasis mine):

His complexion was extremely pale and cadaverous, and he stooped heavily from poring over ancient tomes and no less ancient maps. He moved always with the slow, meditative pace of one who dwells among far-off memories and reveries; and he spoke often of people and events and ideas that have long since been forgotten. For the most part, he was apparently unheedful of present things, and I felt that for him the huge city of Ptolemides, in which we both dwelt, with all its manifold clamor and tumult, was little more than a labyrinth of painted vapors. There was a like vagueness in the attitude of others toward Tomeron; and though he had always been accepted without question as a representative of the noble and otherwise extinct family from whom he claimed descent, nothing appeared to be known about his actual birth and antecedents.

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In History of Friedrich II of Prussia V 4 by Thomas Carlyle, reference is made to the same term, along with an explanatory definition (emphasis mine again):

What is Justice but another form of the REALITY we love; a truth acted out? Of all the humbugs or "painted vapors" known, Injustice is the least capable of profiting men or kings!

Of the different senses of humbug, the most relevant here seems to be the following:

[Merriam-Webster]
2 : an attitude or spirit of pretense and deception
// in all his humbug, in all his malice and hollowness
— Mary Lindsay

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Assuming that painted vapors means pretense and deception, we can paraphrase the original texts.

• The Epiphany of Death: For the most part, he was apparently unheedful of present things, and I felt that for him the huge city of Ptolemides, in which we both dwelt, with all its manifold clamor and tumult, was little more than a labyrinth of pretences and deceptions.
• History of Friedrich II of Prussia V 4: Of all the pretences and deceptions known, Injustice is the least capable of profiting men or kings!

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I would not say that painted vapors is a well known phrase, but it makes sense in this context.

The phrase itself is certainly a metaphor. Vapors invokes something wispy and ephemeral, or foolish or fanciful, and painted, as in gold-painted lead, suggests something fake or superficial, which misleads from its real nature.

An actually common idiom that is very close in meaning to this is fool's gold.