I'm reading Shakespeare's Lives by Samuel Schoenbaum at the moment. The most entertaining parts are where he discusses, dismisses and pokes fun at those who believe someone else wrote Shakespeare's plays.
A lot of the people who believe a grammar school boy from Warwickshire couldn't have written the plays are clearly motivated by snobbery. For example, the barrister Christmas Humphreys wrote in 1955: "It is offensive to scholarship, to our national dignity, and to our sense of fair play to worship the memory of a petty-minded tradesman while leaving the actual author of the Shakespeare plays and poems unhonoured and ignored. Moreover, I have found the plays of far more interest when seen as the work of a great nobleman and one very close to the fountainhead of Elizabethan England." (Humphreys was an unusual member of the Bar, a convert to Buddhism whose North London home is now a temple). They are invariably never - unlike Schoenbaum - academic experts on Shakespeare's plays but rather eccentric amateurs: the pioneer of the theory that the Earl of Oxford wrote the plays was a schoolteacher called, rather appropriately, Looney.
There is now though another element to the anti-Stratfordian movement apart from the snobbery. They increasingly resemble other conspiracy theorists and "truthers" who believe the moon landings were a hoax, 9/11 was carried out by the CIA and/or Mossad etc. in believing that they have secret, "inside" information that "they" (the Government/Jews/academic establishment) don't what us to know.