1 Word
NARUTO
And I'm not saying that just to say it, I mean I knew that the filler had been making the anime infamous but after watching that crappy ass arc they had in the series that takes place after the Tsunade arc I was you do not not how happy I was after they brought that too an end.
just the break down the differences between good&bad filler
Good Filler-Adds depth to the story and it's characters without sacrificing too much in the process the best examples are DB & DBZ (or DragonBall if that's your thing)
Bad Filler- is filler that essentially doesn't belong in anime the because it alters
the story in a negative way ex: Naruto,Rurouni Kenshin,EyeShield21.