To be completely honest, there ARE some moments of weak dialogue in the OT. They're easy to find in ROTJ, as Ford's acting becomes increasingly wooden and the script becomes more formulaic. Even SW, which in my opinion has by far the best dialogue, has its cheesy moments ("flyboy" reminds me of "ex-squeeze-me", and then there's "reach out with your feelings"). But these are only the tiniest of blips compared to the barrage of embarrassing line after embarrassing line in all of the PT movies.

They also serve to show how bad SW could have been. One of the reasons SW was so good is that it was edited masterfully. The SW scenes on the cutting room floor are IMO uniformly awful, including of course the ones put back in for the SE (one thing the SE does, is painfully illustrate how good the original editing was, and how close to catastrophe SW was skating). The story was cheesy B stuff, edited into a tight, effective movie that holds its atmosphere and pop for the entire run. Just read the Lucas novel... the dialogue is overdrawn and clumsy compared to the movie. For dialogue to be good, you need good tight editing, and enough strong takes from which to edit.