Some while ago I posted,
in connection with HG Well's Kipps, about the phenomenon of writers who produce books about central characters who, far from being an idealised and glamorous version of themselves, are quite the reverse: someone who could notpossibly be the person who is writing the book. Artie Kipps is not only fairly dim and gullible, he has none of the get-up-and-git that made HGW HGW.
By reverse Mary Sue I don't mean just writers who carefully avoid writing about people like themselves - George Eliot did this, but a reverse Mary Sue in her case would have been a novel about a would-be provincial blue-stocking who stays in the provinces and does worthy unmarried female relative stuff for her family.
I was musing just now about why Dione in Naomi Mitchison's We Have Been Warned (1935) is such an unsatisfactory character. It's not just that artistic creativity has been hived off to her sister Phoebe, or that she, unlike her husband, doesn't get to have a satisfying extramarital affair. There's an excruciating scene in which she persuades one of her husband's potential constituents to go to a birth control clinic, and I thought, 'Gee, in real life Mitchison was helping run the clinic and getting up fundraising activities and getting involved in the research'. Dione just doesn't have anything like the oomph even though the general outlines of her life are so similar to her creator's.
Lack of oomphiness can work if well done: Arnold Bennett's Edwin Clayhanger is sort of Bennett if he hadn't had all the driving ambition, etc, but Clayhanger doesn't feel like a hollow thing with all the life sucked out of it.
I'm trying to think of other examples, good and bad, but it's too late at night. Which explains any incoherence in the argument.