Aesthetic standards are, of course, subjective, and few arguments descend into pointlessness, point-scoring, and appeals to the authority of popularity/mass appeal/"the test of time"  more quickly than those regarding quality.
You could be talking about music...
"Led Zeppelin RULES"
-> "Wrong, they SUCK!"
-> "You don't have to like them, but you gotta respect their chops!"
-> "But they RIPPED OFF all those bluesmen!"
-> "Well, they must have been doing SOMETHING right because they're still the undisputed kings of ROCKING when those bluesmen are FORGOTTEN!"
-> And so on
"Jackson Pollack? My 5-year-old could do that! And Thomas Kinkade might be the most successful painter alive but he's also the worst!"
"In 200 years, no one will remember Anne Geddes [I know, not a painter, whatever], but people will still be studying Picasso. I like Picasso. You like Anne Geddes. Nuff said."
"We still read Shakespeare while many of his contemporaries lie forgotten because his works speak to deeper truths that everyone can relate to."
"Blah, blah, blah, Gilgamesh, Beowulf, archetypes, God, the Bible."
...and so on. I don't need to dig up every argument about the Oprah book club or Harold Bloom's canon or whatever; you know what I'm talking about. It's a black hole drawing in authenticity and influence and commercialism and everything else, and a lot of the time it gets unbelievably stupid to argue about what we'll be reading/watching/listening to in the years to come as if that had any bearing on what we should pay attention to now. This is (in part) because there's a huge arbitrary element to what remains or gains popularity over time (and adding preservation into the equation, it becomes more random the farther back you go -- though everything is going to change with the Internet and electronic storage, of course). But regardless of the reasons to which you attribute his continued survival, Shakespeare's still around, and the question of why some authors have endured and some haven't can be an intriguing one -- so far as it illuminates the virtues of the texts themselves.
Which brings us to What Can Be Saved From The Wreckage, a brief but fascinating overview of James Branch Cabell's works, both major and minor. Author Michael Swanwick sets the context :
It is hard to imagine today the magnitude of James Branch Cabell's fame in the early part of the last century. Cabell's books were Mark Twain's chief reading in the great humorist's declining years. Theodore Roosevelt received him at the White House. The occultist Aleister Crowley harried him with fan letters. H.L. Mencken was his advocate. [...] Sinclair Lewis, accepting the Nobel Prize for Literature in 1930, mentioned him as one of a number of writers who might reasonably have won it. (p. 1)
Cabell enjoyed both critical adulation and widespread popularity (only partly owing to Jurgen's major obscenity scandal). He's significant to the development of the field of literary fantasy. He ticked off every box towards what you'd think would lead to a lasting readership. Now he's almost completely forgotten.
How did he drop off the map? That's a good question, and the answer is complicated.
Swanwick argues convincingly that, rather than owing to flaws in the works themselves , Cabell's slide into obscurity was primarily self-inflicted, the result of fucking over his readers with a uniform edition of his books. Yes, it's worth noting that Cabell was, in fact, an early victim of the infamous Brain Eater , insisting that his collected works formed a monstrous 18 volume "unified philosophical meditation on Life and Mankind" called the Life of Manuel that must be evaluated as a whole and whose component books were both necessary and of equivalent quality (erecting as many impediments to reader accessibility as possible). He revised previous books to insert unnecessary connections to later works and produced pointless genealogies and bad poetry "by" his characters. Later on, he abridged his name, decided he would be writing very different books, and proceeded to write very similar but worse books as his talent waned, his readership lost patience, and his sales dropped.
Still, Swanwick concludes that Cabell's body of work definitely contains enough greatness to warrant a readership (and justifies this with plenty of evidence). Without lamentation, Swanwick acknowledges Cabell's current obscurity and sets out to evaluate the extensive body of work (about 60 books, many of them incredibly hard to find) with the objective of determining which books are worth seeking out (and why), which are of interest only to fans or rely on knowledge of Cabell's other books for their effect, and which are merely forgettable, aimless, unpleasant, or dull.
His analysis is really compelling, to no surprise if you're already familiar with Swanwick as author of innovative SF or as a fantastic critic and essayist (if you haven't read The Postmodern Archipelago, read it right now. There's an elegant encapsulation of how fantasy operates in "In The Tradition" that just *gets* it, absolute truth-wise). He makes me want to read the books he concludes to be vital (reducing the essential Cabell to a much more manageable 6) and he has insightful reasons for rejecting the books he rejects.
Do I believe that this book will lead to Cabell's better books coming back into print, or that it will have any significant effect on Cabell's future reputation or critical reception? Not really; this is, after all, a small press-published essay with a print run of about 200 (if you can find this, snap it up) written by a SF writer who's great and somewhat obscure himself. But it is wonderful as a reader's guide (all I have is a copy of the Ballantine reprint of The Silver Stallion, which I think I read without comprehension at the age of, like, 6 and might not have touched again without the context this puts it in) and a work of nuanced and evenhanded criticism of a sorely unappreciated major author, and it raises provocative questions about the bizarre process by which literature stands or falls over time.
 Whether as a good or bad thing; see indie rock and the cult of obscurity, or the classical music community and attitudes toward lasting popularity. We get into the issue of taste here, which is every bit as loaded and complex, but I'm sidestepping it except to remember to check out Carl Wilson's 33 1/3 book dealing with the subject through a look at Celine Dion. Now that's a good premise right there!
 For the stupidity aspect, I love Scharpling and Wurster's Rock, Rot & Rule, in which Jon Wurster's character's book of music criticism does nothing but classify bands on the basis of whether they "rock," "rot," or "rule" for the most hilariously dumb reasons possible and people actually call in to argue with him.
 And these flaws certainly aren't ignorable, since (for example) Cabell's sexism in many cases informs the heart of his stories, with men chasing after idealized beauties or settling for shrewish wives; his attitudes towards life are inseparably linked with his attitudes towards women. A modern reader can't read Cabell without some legitimate problems. Plus there are, of course, some books that suck.
 It's especially interesting because it adds context to the twilight of Heinlein's later career. I already knew that Heinlein makes plenty of Cabell references and that Job: A Comedy Of Justice is his most Cabellian novel, but now I can see that he was following in Cabell's footsteps with his unconvincing attempts to create a unified fictional universe, making it clear that at least he knew what he was trying to do with his later work, however unsuccessful the implementation. Still remaining to be answered: the question of WHAT'S THE POINT?