Apologies---I forgot to mention that Anthony Stadlen's much-to-the-point comment "Surely, VN's style cannot be judged by what he makes his "creature" Humbert do with HIS "fancy prose style", explicitly acknowledged by "Humbert" on his first page."
 
This observation amplified in ADA where VN even provides a marvellous description of  one of Ada's speech styles. 
 Arch and grandiloquent, Ada would be describing a dream, a natural history wonder, a special belletristic device — Paul Bourget’s ‘monologue intérieur’ borrowed from old Leo — or some ludicrous blunder in the current column of Elsie de Nord, a vulgar literary demimondaine who thought that Lyovin went about Moscow in a nagol’nïy tulup, ‘a muzhik’s sheepskin coat, bare side out, bloom side in,’ as defined in a dictionary our commentator produced like a conjurer, never to be procurable by Elsies. Her spectacular handling of subordinate clauses, her parenthetic asides, her sensual stressing of adjacent monosyllables (‘Idiot Elsie simply can’t read’) — all this somehow finished by acting upon Van, as artificial excitements and exotic torture-caresses might have done, in an aphrodisiac sinistral direction that he both resented and perversely enjoyed.