I realized the prequels sucked a few days before the premiere of TPM.
I was in a Walgreens and they had a huge tie-in merchandizing campaign, with the likeness of Jar-Jar, Anakin, or Darth Maul on almost every product you could imagine. There was a display with the film's children's storybook edition, and I took a glance at it. Right there and then I knew it was a total stinker.