Though I agree that the Scorpion thingamabob in The Mummy Returns looked horrible, I think it should be noted that it was rushed work. I cant remember the details, but I remember reading that a last minute change by the director combined with running out of time resulted in the entire sequence having to be done very quickly. i belive the original idea was to use CG to do the creatures body but they wanted to film The Rock's real face with live action footage and composite that onto the CG creature, but they didnt have time to do so. Hence the rushed, bad CG work we saw.
I have to add the CGI in ANY of the Star Wars Prequel trilogy, namely because every time there was a scene where the actors were all green screened, with all of the action or creatures to be put in LATER, with CGI, the performers looked either bored or clueless.
The worst one the always comes to mind is the flying toothy creatures at the end of the movie "The Langoliers". I know this was a TV movie, but sorry, my suspension of disbelief only goes so far...
I hate just about everything associated with CGI, but the worst thing about it is when it's used to substitute for people... like James Bond in DIE ANOTHER DAY, or Peter Parker running across the rooftops. It was especially fake and disgraceful in BLADE 2, and I got so annoyed that I sarcastically stood up in the theater while watching that mess and frantically pretended that I was playing a video game, working the joysticks... it was just so cartoony.
What gets me is, so many people ACCEPT this, and LIKE it!
In Beyond Borders, there are several scenes with a cgi child dying of starvation. I watched this the other night and was awestruck at first -- you know that feeling when your brain tells you what you are seeing is not right somehow? That's what I felt. I can only assume that either the filmmakers did not want to exploit some little kid or they wanted to show the horrors of starvation by ramping up the "reality" with cgi. in either case, it did not work.
Other than that, The Mummy Returns sequence with the Scorpion King sucked hard.
I haven't seen "Beyond Borders" so I can't comment on the quality of the CGI in question but I do know that people often see something practically impossible in CGI and dismiss it as fake when it's completely well-done.
The first example that comes to mind is the brain-eating scene in "Hannibal". I think the CGI (which I believe amounted to combining Ray Liotta's face from the incision down with a practical puppet) is flawless but people went on and on about how fake it looked.
Well, it does look fake because there's no way that any actor is going to allow the top of his head to be removed so that he can be fed a piece of his brain.
Provided it's well-done, the only time CGI truly doesn't look fake is when it's showing something that wouldn't necessarily have to be done in CGI in the first place. Change the color of the sky slightly and nobody will notice but even a photorealistic monster or spaceship will look fake by it's very nature.
What amazes me is that I have never found a thread critical of stop-motion (or even go-motion) technology, and how fake that can look. I am not flaming those who worship the ground Ray Harryhausen walks on, merely pointing out that to many, it is "six-of-one to half-dozen-of-the-other". For me, if the story is strong enough I can excuse some bad CGI work: It is not a forgone conclusion that it will "take me out of the movie", because my enjoyment of it is not completely dependent on the execution. I would almost pay real money to see LotR done with stop motion. But, as with everything, there is a time where CGI (or stop-motion, for that matter; though the only example I can think of are the AT-ATs in ESB) is appropriate, but either can be over-done. Personally, I would rather see a (mostly) photo-realistic CGI 25ft rampaging gorilla that the stop-motion counterpart (not to disparage that in any way. I fully realize it represented a huge milestone in the evolution of VE). Just my 2 cents - flame away. ..
Pinata: Survival Island has the worst I've ever seen.
For theatrical release, I'd say A Sound of Thunder, especially the flooded subway sequence, which looked like something off of the original Playstation.