I know well the thinking of literary sleuths searching for clues about authorial mysteries, as I was involved in quite a good literary mystery back in 1993, not long after I began my newsletter, New Philistine. I had more actual evidence to go by than do the deVere people. I bolstered my thesis with additional "evidence" taken from the person's writings. Extremely strong inferential evidence-- ultimately meaningless.
At the time I was at the bottom of my existence on this planet; living in Detroit's infamous Cass Corridor, drinking a bottle a day. The newsletter was started as merely an outlet, a forum for ranting created on a ten-dollar used manual typewriter bought in a resale shop. I mailed out free copies to zeensters and to literary people and was surprised to obtain a steady paying readership.
The literary mystery I stumbled upon, through information in a reference biography, became a several-month obsession for me (especially after my expose made New York City newspapers). I saw it as a ticket out of oblivion. Not the oblivion of being unknown, but actual personal oblivion; such as, "I'm going to drink myself into oblivion," a favorite saying of mine at the time.
How much can we know about an author from his writings? I once saw novels as true snapshots of an individual's mind. But one has to take into account the writer's willingness to fool and play with the reader. (Shakespeare does it constantly.)
The case I'd made was startling-- and never answered, only squelched. (Even in this, the subject was likely playing.) I encountered walls of secrecy-- and incidentally was introduced by mail for the first time to George Plimpton, master patron of young establishment literary people.
Against the hurricanes of inference and conjecture, hints, clues, and implications, one needs the touchstone of hard evidence. Documented evidence. When I found an additional piece of same indicating I might be wrong, I dropped the matter and went on to other things. But my curiosity about the NYC lit world and how it operated, and what the people were like-- they seemed the opposite of candid and honest-- had been stimulated.
Now-- another mystery. Are there any literary sleuths out there who wish to tackle a mystery more current than ridiculous theories about Shakespeare? Here's one: Find out why Lewis Lapham was fired by Harper's in the early 80's, and what controversy involving his magazine preceded it. (That he was rehired a year later indicates the firing was meant to quiet the controversy.)