We have an excellent facsimile of the Third Folio, which appeared in 1663, and a second issue in 1664, augmented, as the title-page tells us, with seven plays:  Pericles; The London Prodigall; The History of Thomas Lord Cromwell; Sir John Oldcastle Lord Cobham; The Puritan Widow; A York-Shire Tragedy; The Tragedy of Locrine.  Only Pericles is considered to be Shakespeare’s (partially)

Because of their scarcity relative to the other folios, it is though that many were destroyed before distribution in the London fire of 1666.

According to one of the standard scholarly works on the subject, the Third Folio “does more credit to the printing house which turned it out and is largely free from gross typographical errors. But from the fact that it unintentionally omitted a great many words, we infer that the proof reading given it was not sufficiently careful to catch unobtrusive compositor’s errors. The editor, furthermore, was not nearly so aggressive as the editor of F2 [2nd Folio] and did not feel free to go further than to correct blunders that make nonsense of meaning, grammatical improprieties, an archaic diction.”

–Black & Shaaber, Shakespeare’s Seventeenth-Century Editors, 1632-1685 (1937), who identify 943 editorial changes made in the Third Folio.