Smallville - It’s just gotten dumb, and they basically retread the same three plots over and over (how many times have we seen a variation on the “bad person inhabits the bodies of various cast members and wreaks havoc” bit?)
CSI - It’s gone from being a cool police procedural with a focus on solving the case by following the evidence, to “who cares about the case or the evidence, we just want to showcase a new bizarre lifestyle every month.” The murder has become just a MacGuffin. The evidence has become unimportant, cases are now “solved” by someone’s deductive leap from nowhere.
Shows I’m almost ready to give up on, but will give them one more chance:
Joan of Arcadia - It’s gone from a nice, reasonable happy show where at least the audience got to see the good that came from Joan’s actions, to a “nobody gets to be happy” show where most episodes have no point. And now, appparently, next season we get “the nemesis”. Joan doesn’t need a nemesis, she just needs some writers with imagination.
Stargate Atlantis - Dumb, dumb, dumb, dumb. And did I mention that it’s dumb? The Major is the only worthwhile character, all the rest (especially Dr. Weir!!) need to be sucked dry by the Wraith and replaced. It’s got such potential, though, that’s just being wasted, wasted, wasted!
Everwood - It’s gone from a reasonably pleasant series to just a soap opera with a bigger budget. And is Ephraim the dumbest kid who’s ever lived or what? Hey, I’m going to throw away my entire future, the girlfriend who loves me, my relationship with my father, and everything else, just because I can’t wait another two days to fly off and gaze at the house where my son lives???
Stargate SG-1 - I’ll try it for at least a couple of episodes with the doofus from Farscape, but he’s just not fit to lick the bootprints of Richard Dean Anderson. I just don’t think the remaining three will be able to make up for the loss of O’Neil. The writers have pretty much run out of ideas anyway, they should have cancelled it and let it go out gracefully.