It's getting harder and harder to watch The Simpsons when they don't even make the slightest attempt to foster continuity any longer. Why would Cletus and family have to introduce themselves to the Simpsons? Didn't Bart almost get married to one of Cletus' daughters just a couple of seasons ago?
Aside from that, I didn't quite get the reveal at the end... how did Lisa discover the truth about the town's blindness? Used to be The Simpsons did a great job at not only producing twist endings, but at properly explaining said twist ending without having to resort to deliberately foreshadowing it earlier in the episode.
The Flanders scene was funny, though, so I guess it wasn't a total loss.