Good series end. Bad series drag on and get milked, essentially turning into a DBZ clone.
Good series: Outlaw Star. 26 Episodes. Any more and there would have been filler.
Good Series: Cowboy Bebop. Again, 26 episodes. The entire series was itself, nothing but filler, only 4 or 5 of the episodes actually having anything to do with an actual story.
Good Series: Rurouni Kenshin. 95 episodes. It ended up dragging on, but they did it in a graceful way, ending the series when it needed to be end, before things got bad.
Bad Series: Naruto. 220 Episodes. I will say, the first and most of the second season were good. I used to enjoy it alot. In fact, im sure if i dig through my closet i can find a headband or two. But it drags on and on and on and on. And its still going. WHY? Why must you still keep going?
Bad Series: Full Metal Alchemist. 111 Episodes. Again, at first, it was a great anime. I liked it for about the first 30 or so episodes. But then they decide, lets tank the series with another 21 episodes, full of massive plot holes you can fly a Gundam through. But that wasnt enough. Then, they wonder how they can milk its fame more. OH! I know! Lets redo the entire series a little more true to the story this time, but make it drag on for an additional 13 episodes, bringing its total to 64. A combined 111 episodes, half of which you already watched, because you saw the first series.
Theres a difference between a "Bad Anime" and a "Bad series". Look at Star Wars. The first 3 made were a Master Piece of cinema. The following 3, which were a prequel to the first 3, were pretty bad. The series itself was bad, because 3 really bad movies are involved in it.
Naruto is by no means a Bad Anime. And i dont hate it. I hate where it went.