I'd say the worst example is the anime of Rosario+Vampire. Now, it's a harem show, so of course it's going to be blatant about it, but I've read the manga as well, and believe me, the adaption is much more... Shameless. Too bad too, because Rosario actually has a pretty good plot that gets really dumbed down in the Anime, and that's the form of it most people remember.
Oh, and One Piece is pretty bad with it too. Especially Nami
As you can see, she certainly got some... "Character development" post time-skip
Oh, and One Piece is pretty bad with it too. Especially Nami
As you can see, she certainly got some... "Character development" post time-skip