Kenshin OVA.  

I know I'm in the minority in this opinion, but 
I first watched the entire Kenshin TV series and 
I loved it... humor, drama, action.. characters 
I loved... I think its a great show. 

Then I watched the OVAs... I detest the art 
style, it's ugly as sin.. and those eyes in the 
second OVA... those eyes!!  I couldn't 
concentrate on the story cause I kept thinking 
they were going to steal my soul!! O_O  LOL. 

And I found the stories to be very boring in 
both OVAs.  *yawn*  I don't understand how that 
depressing Kenshin turned into the Kenshin from 
the TV series, or how he turned back come the 
second OVA.  So it felt like a completely 
different series.. one that I didn't enjoy at 
all and was painful to watch.

Other than that.. I haven't seen any REALLY bad 
anime.  I really don't like DBZ, but that just 
comes from the few I caught on cartoon network a 
couple years ago.  I don't like the art style so 
it just irks me whenever I see cels/merchandise 
from that series.  .hack//sign... left a lot to 
be desired, though even so, I can't bring myself 
to say I hated the show.  Something about it 
keeps me from saying that, despite all the rants 
I can make about that show.. :P

So yeah... Kenshin OVA so far is the worst I've 
really seen.  *hides from OVA fans*