Victor’s description of Ferdinand is some pretty scathing stuff. Ferdinand, sucking on moonstone candy, wearing a waterproof coat, and carrying a camera, is the epitome of the tacky tourist, and like Victor, we struggle to understand Nina’s marriage to this complete fop.
But then we remember that Victor is the one telling the story, and he’s likely indulging in a little hyperbole. Just read the description of Ferdinand’s circle of friends, men with useless hobbies, overblown opinions, and pretentious attire. It looks like something of a caricature.
There are a few common theories to go along with this venomous windbag. One is that Ferdinand is very much like Victor, which explains why Victor hates him so much. We talk more about this when we discuss the pair as a foil elsewhere. Another theory is that Nabokov is mocking himself – that Ferdinand embodies all of the author’s own traits, in a comically exaggerated manner. Nabokov hated literary criticism, as does Ferdinand. Nabokov is also known for his complex prose; he is, like Ferdinand, "a weaver of words" who writes about the fictional in what is occasionally a nearly "unintelligible" way. Check out the one passage of Ferdinand's prose that we do get to see:
Her face was rather nature’s snapshot than a meticulous portrait, so that when…tried to imagine it, all he could visualize were fleeting glimpses of disconnected features: the downy outline of her pommetttes in the sun, the amber-tinted brown darkness of quick eyes, lips shaped into a friendly smile which was always ready to change into an ardent kiss.
Compare this to this passage from Nabokov’s Lolita:
There are two kinds of visual memory: one when you skillfully recreate an image in the laboratory of your mind, with your eyes open (and then I see Annabel in such general terms as: "honey-colored skin," "thin arms," "brown bobbed hair," "long lashes," "big bright mouth"); and the other when you instantly evoke, with shut eyes, on the dark innerside of your eyelids, the objective, absolutely optical replica of a beloved face, a little ghost in natural colors (and this is how I see Lolita).
Of course, Lolita was written decades AFTER "Spring in Fialta", but Nabokov’s prose is somewhat constant, at least stylistically, over time (as are the themes he focuses on, which you can see here). Ferdinand mirrors Nabokov’s style and thematic predilections, leading us to believe that the author is hiding behind his most detestable character.