This diffusion of appreciation among the common herd was in fact one of the sorest trials of his life; unaccountable triumphs had for ever spoilt his enjoyment in pictures and books he had once held dear; the approbation of the general voice always ended by making him discover some hitherto imperceptible blemish, and he would repudiate them, asking himself if his taste was not getting blunted and untrustworthy.
In addition to being a proto-hipster, des Esseintes is a proto-MRA/PUA, and the kind of atheist who had a religious upbringing and therefore spends all his time obsessively arguing theology, and worrying that he might some day believe it, because then his teachers will have won. I'm not sure how much of this was intended as satire by the author -- I think the passages on decor are serious, as well as the lengthy descriptions of des Esseintes' library (part of the point of this novel seems to be to collect and summarize all the books the author likes, for the benefit of readers who can't get their hands on them), but I'm not sure des Esseintes himself is -- he has too many failures. His exotic plants all die of neglect, and his attempt to turn a working-class teenager to crime does not result in the lad's name showing up in the newspaper for having murdered anybody. His only happy chapter is when he decides to see England and gets as far as an English restaurant catering to travelers. To his delight, they all remind him of Dickens characters. Eventually he decides the real England would only disappoint him -- after all, the Netherlands turned to not be anything like a Bruegel painting in real life -- so he turns around and goes home satisfied until the following chapter when he has another nervous collapse. I think he probably gets laid more often than his modern-day successors, but that's because, as a wealthy 19th-century aristocrat, he can pretty much just pay for sex; one of the many things that annoy him about modern life is that brothels are gradually being replaced with taverns, where one has to flirt with the waitresses rather than just buy them:
Des Esseintes could not help exclaiming, what simpletons these fools must be who flutter round beer-halls, for, to say nothing of their ridiculous self-deception, they have positively brought themselves to ignore the danger they run from the low-class, highly suspicious quality of the goods supplied, to think nothing of the money spent in drinks, all priced beforehand by the landlady, to forget the time wasted in waiting for delivery of the commodity, — a delivery put off and put off continually in order to raise the price, frittered away in delays and postponements endlessly repeated, all to quicken and stimulate the liberality of the client.
In any case, based on his flashbacks, des Esseintes still ended up disappointed with his mistresses' non-resemblance to his fantasies; the big muscular circus acrobat turned out to not be kinky or dominant, and the ventriloquist dumped him when she got fed up with his insistence that she throw her voice when they were in bed together. So, yeah, basically, he's the That Guy of 19th-century French literature.