Solid or sullied?

Hamlet was printed in three versions, two in Shakespeare's life, one just after: an anomalous quarto of 1603 (sometimes thought to have been pirated), a second, authorised version (shown here) in 1604, and the Folio text of 1623. All vary considerably one from the other.

The Quarto

The Folio

How insistent can we be about a particular interpretation of the play, if there is some doubt about what Shakespeare actually wrote? Is it possible that he actually revised the play between the various printings--in which case should we ignore the earlier versions (which would mean leaving out at least one of the major soliloquies)?

• Well, was Hamlet's flesh too solid or sullied?
• A play revised
• How bad was the "bad" quarto?