None that I can really think of, but there has been series were I didn't like it or care for it, but there were a few characters I liked. So kinda.

Even though LOK isnt an anime, I only watched it for Amon. Didnt care for the plot but it sucked anyway.
Another one would Bleach, right near the end of the anime. I loved the story line up until they ended the Arrancar arc. After that, I didnt finish the last season, Ulquiorra (my favorite), Grimmjow, every arrancar, gone. It was the best arc yet and they're all gone.
But hardly a case.

Yes~
Free! (although I'm kinda interested to see where the story will go), Durarara and K-ON.

I'm watching Free! obviously just to see dem bishies. Doubt that I'll get myself into any series with a plot that doesn't interest me any time soon.

Yes,Ghost Stories does come to mind for me here.

No. I would stop watching the series if I don't like the story, even if I like the characters.

I usually watch shows for the characters, but if I'm going to like the anime, of course I'm gonna have to be into the story as well. So a good anime to me would have both. Though there are some series (like Hetalia) that don't have much of a story anyway. XD

I only clicked this since Rin is in the picture!
. . . . . . . No I didn't!

It's soul eater! I've never really thought about the story that much, but all the characters are so unique and awesome that I just wanna watch it anyways!

Only one I can think of is K-On! I absolutely adore all of the characters. But I never really payed much attention to the story~

Masamune-kun no Revenge. Don't like the story at all and there are only two characters out of the anime that I actually ended up liking.