I'll be honest guys, I thought Yoda started sounding goofy in ROTJ. It was a short scene before he died, but he started talking backwards too much then. Just compare him in ESB with the other 4 movies he appears, it is almost like he is a different character. In ESB, he truly shines in that movie, and the fact that he is a puppet, and steals every scene on Dagobah is truly remarkable. He talks backwards a few times in ESB, but not nearly as much as the other 4 movies after.

I look at it this way with Yoda and everything in SW. It all started to crumble in ROTJ, but not enough where it was noticably bad, then when it gets to the PT movies, it just gets really bad. The humor, the dialogue, Yoda, The Emperor, the acting, the plots of the stories, and the plot holes. If you really look at ROTJ, it all started there, and then once the SE & PT were released, the floodgates opened and the saga went from great to mediocre. But don't get me wrong, I still love ROTJ, I just notice now how inferior in quality it is to SW & ESB.